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Recent Mozilla Firefox Security Advisories

Advisory Title Published
mfsa2021-20 Security Vulnerabilities fixed in Firefox 88.0.1, Firefox for Android 88.1.3 mfsa2021-20 May 5, 2021
mfsa2021-18 Security Vulnerabilities fixed in Firefox ESR 78.10.1 mfsa2021-18 May 4, 2021
mfsa2021-15 Security Vulnerabilities fixed in Firefox ESR 78.10 mfsa2021-15 April 19, 2021
mfsa2021-16 Security Vulnerabilities fixed in Firefox 88 mfsa2021-16 April 19, 2021
mfsa2021-11 Security Vulnerabilities fixed in Firefox ESR 78.9 mfsa2021-11 March 23, 2021
mfsa2021-10 Security Vulnerabilities fixed in Firefox 87 mfsa2021-10 March 23, 2021
mfsa2021-08 Security Vulnerabilities fixed in Firefox ESR 78.8 mfsa2021-08 February 23, 2021
mfsa2021-07 Security Vulnerabilities fixed in Firefox 86 mfsa2021-07 February 23, 2021
mfsa2021-06 Security Vulnerabilities fixed in Firefox 85.0.1 and Firefox ESR 78.7.1 mfsa2021-06 February 5, 2021
mfsa2021-04 Security Vulnerabilities fixed in Firefox ESR 78.7 mfsa2021-04 January 26, 2021

@firefox Tweets

Dread opening your browser? While we can’t change the work that awaits you, we do have extensions and tools to make… https://t.co/ifvXPtkg6a
Wed May 12 13:15:05 +0000 2021

If there's one thing we believe in, it's personal privacy online. So next time you wanna do literally anything pr… https://t.co/PRHXaba7jS
Tue May 11 18:45:51 +0000 2021

You know those sites with check boxes that read: "Don’t uncheck this box if you don’t not want to hear from us!”… https://t.co/c7MA6euDSh
Fri May 07 19:25:02 +0000 2021

Detroit is a microcosm of a larger problem across the nation, but during the pandemic the digital divide has become… https://t.co/AqCdNTFZev
Thu May 06 23:01:01 +0000 2021

RT @TheWebbyAwards: Vote for your favorite: 3-seed @mitchellbaker (CEO, @mozilla) "Demand Better Of The Internet.'" vs 14-seed @humansofny…
Wed May 05 19:58:39 +0000 2021

By the Year

In 2021 there have been 46 vulnerabilities in Mozilla Firefox with an average score of 7.1 out of ten. Last year Firefox had 132 security vulnerabilities published. Right now, Firefox is on track to have less security vulnerabilities in 2021 than it did last year. Last year, the average CVE base score was greater by 0.28

Year Vulnerabilities Average Score
2021 46 7.07
2020 132 7.36
2019 107 7.66
2018 102 7.77

It may take a day or so for new Firefox vulnerabilities to show up in the stats or in the list of recent security vulnerabilties. Additionally vulnerabilities may be tagged under a different product or component name.

Recent Mozilla Firefox Security Vulnerabilities

A texture upload of a Pixel Buffer Object could have confused the WebGL code to skip binding the buffer used to unpack it

CVE-2021-23981 8.1 - High - March 31, 2021

A texture upload of a Pixel Buffer Object could have confused the WebGL code to skip binding the buffer used to unpack it, resulting in memory corruption and a potentially exploitable information leak or crash. This vulnerability affects Firefox ESR < 78.9, Thunderbird < 78.9, and Firefox < 87.

Buffer Overflow

Using techniques that built on the slipstream research, a malicious webpage could have s

CVE-2021-23982 6.5 - Medium - March 31, 2021

Using techniques that built on the slipstream research, a malicious webpage could have scanned both an internal network's hosts as well as services running on the user's local machine utilizing WebRTC connections. This vulnerability affects Firefox ESR < 78.9, Thunderbird < 78.9, and Firefox < 87.

Inadequate Encryption Strength

By causing a transition on a parent node by removing a CSS rule

CVE-2021-23983 6.5 - Medium - March 31, 2021

By causing a transition on a parent node by removing a CSS rule, an invalid property for a marker could have been applied, resulting in memory corruption and a potentially exploitable crash. This vulnerability affects Firefox < 87.

Buffer Overflow

A malicious extension could have opened a popup window lacking an address bar

CVE-2021-23984 6.5 - Medium - March 31, 2021

A malicious extension could have opened a popup window lacking an address bar. The title of the popup lacking an address bar should not be fully controllable, but in this situation was. This could have been used to spoof a website and attempt to trick the user into providing credentials. This vulnerability affects Firefox ESR < 78.9, Thunderbird < 78.9, and Firefox < 87.

Authentication Bypass by Spoofing

If an attacker is able to alter specific about:config values (for example malware running on the user's computer), the Devtools remote debugging feature could have been enabled in a way

CVE-2021-23985 6.5 - Medium - March 31, 2021

If an attacker is able to alter specific about:config values (for example malware running on the user's computer), the Devtools remote debugging feature could have been enabled in a way that was unnoticable to the user. This would have allowed a remote attacker (able to make a direct network connection to the victim) to monitor the user's browsing activity and (plaintext) network traffic. This was addressed by providing a visual cue when Devtools has an open network socket. This vulnerability affects Firefox < 87.

Exposure of Resource to Wrong Sphere

A malicious extension with the 'search' permission could have installed a new search engine whose favicon referenced a cross-origin URL

CVE-2021-23986 6.5 - Medium - March 31, 2021

A malicious extension with the 'search' permission could have installed a new search engine whose favicon referenced a cross-origin URL. The response to this cross-origin request could have been read by the extension, allowing a same-origin policy bypass by the extension, which should not have cross-origin permissions. This cross-origin request was made without cookies, so the sensitive information disclosed by the violation was limited to local-network resources or resources that perform IP-based authentication. This vulnerability affects Firefox < 87.

Origin Validation Error

Mozilla developers and community members reported memory safety bugs present in Firefox 86 and Firefox ESR 78.8

CVE-2021-23987 8.8 - High - March 31, 2021

Mozilla developers and community members reported memory safety bugs present in Firefox 86 and Firefox ESR 78.8. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox ESR < 78.9, Thunderbird < 78.9, and Firefox < 87.

Buffer Overflow

Mozilla developers reported memory safety bugs present in Firefox 86

CVE-2021-23988 8.8 - High - March 31, 2021

Mozilla developers reported memory safety bugs present in Firefox 86. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 87.

Buffer Overflow

Mozilla developers reported memory safety bugs present in Firefox 84 and Firefox ESR 78.6

CVE-2021-23964 8.8 - High - February 26, 2021

Mozilla developers reported memory safety bugs present in Firefox 84 and Firefox ESR 78.6. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 85, Thunderbird < 78.7, and Firefox ESR < 78.7.

Buffer Overflow

Mozilla developers reported memory safety bugs present in Firefox 84

CVE-2021-23965 8.8 - High - February 26, 2021

Mozilla developers reported memory safety bugs present in Firefox 84. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 85.

Buffer Overflow

Mozilla developers reported memory safety bugs present in Firefox 85 and Firefox ESR 78.7

CVE-2021-23978 8.8 - High - February 26, 2021

Mozilla developers reported memory safety bugs present in Firefox 85 and Firefox ESR 78.7. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 86, Thunderbird < 78.8, and Firefox ESR < 78.8.

Mozilla developers reported memory safety bugs present in Firefox 85

CVE-2021-23979 8.8 - High - February 26, 2021

Mozilla developers reported memory safety bugs present in Firefox 85. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 86.

Buffer Overflow

If a user clicked into a specifically crafted PDF

CVE-2021-23953 4.3 - Medium - February 26, 2021

If a user clicked into a specifically crafted PDF, the PDF reader could be confused into leaking cross-origin information, when said information is served as chunked data. This vulnerability affects Firefox < 85, Thunderbird < 78.7, and Firefox ESR < 78.7.

Using the new logical assignment operators in a JavaScript switch statement could have caused a type confusion

CVE-2021-23954 8.8 - High - February 26, 2021

Using the new logical assignment operators in a JavaScript switch statement could have caused a type confusion, leading to a memory corruption and a potentially exploitable crash. This vulnerability affects Firefox < 85, Thunderbird < 78.7, and Firefox ESR < 78.7.

Object Type Confusion

The browser could have been confused into transferring a pointer lock state into another tab, which could have lead to clickjacking attacks

CVE-2021-23955 6.1 - Medium - February 26, 2021

The browser could have been confused into transferring a pointer lock state into another tab, which could have lead to clickjacking attacks. This vulnerability affects Firefox < 85.

Clickjacking

An ambiguous file picker design could have confused users who intended to select and upload a single file into uploading a whole directory

CVE-2021-23956 6.5 - Medium - February 26, 2021

An ambiguous file picker design could have confused users who intended to select and upload a single file into uploading a whole directory. This was addressed by adding a new prompt. This vulnerability affects Firefox < 85.

Navigations through the Android-specific `intent` URL scheme could have been misused to escape iframe sandbox

CVE-2021-23957 7.4 - High - February 26, 2021

Navigations through the Android-specific `intent` URL scheme could have been misused to escape iframe sandbox. Note: This issue only affected Firefox for Android. Other operating systems are unaffected. This vulnerability affects Firefox < 85.

The browser could have been confused into transferring a screen sharing state into another tab, which would leak unintended information

CVE-2021-23958 6.5 - Medium - February 26, 2021

The browser could have been confused into transferring a screen sharing state into another tab, which would leak unintended information. This vulnerability affects Firefox < 85.

Exposure of Resource to Wrong Sphere

An XSS bug in internal error pages could have led to various spoofing attacks, including other error pages and the address bar

CVE-2021-23959 6.1 - Medium - February 26, 2021

An XSS bug in internal error pages could have led to various spoofing attacks, including other error pages and the address bar. Note: This issue only affected Firefox for Android. Other operating systems are unaffected. This vulnerability affects Firefox < 85.

XSS

Performing garbage collection on re-declared JavaScript variables resulted in a user-after-poison, and a potentially exploitable crash

CVE-2021-23960 8.8 - High - February 26, 2021

Performing garbage collection on re-declared JavaScript variables resulted in a user-after-poison, and a potentially exploitable crash. This vulnerability affects Firefox < 85, Thunderbird < 78.7, and Firefox ESR < 78.7.

Further techniques that built on the slipstream research combined with a malicious webpage could have exposed both an internal network's hosts as well as services running on the user's local machine

CVE-2021-23961 7.4 - High - February 26, 2021

Further techniques that built on the slipstream research combined with a malicious webpage could have exposed both an internal network's hosts as well as services running on the user's local machine. This vulnerability affects Firefox < 85.

Incorrect use of the '<RowCountChanged>' method could have led to a user-after-poison and a potentially exploitable crash

CVE-2021-23962 8.8 - High - February 26, 2021

Incorrect use of the '<RowCountChanged>' method could have led to a user-after-poison and a potentially exploitable crash. This vulnerability affects Firefox < 85.

When sharing geolocation during an active WebRTC share

CVE-2021-23963 4.3 - Medium - February 26, 2021

When sharing geolocation during an active WebRTC share, Firefox could have reset the webRTC sharing state in the user interface, leading to loss of control over the currently granted permission. This vulnerability affects Firefox < 85.

Improper Preservation of Permissions

Firefox for Android suffered from a time-of-check-time-of-use vulnerability

CVE-2021-23977 5.3 - Medium - February 26, 2021

Firefox for Android suffered from a time-of-check-time-of-use vulnerability that allowed a malicious application to read sensitive data from application directories. Note: This issue is only affected Firefox for Android. Other operating systems are unaffected. This vulnerability affects Firefox < 86.

TOCTTOU

If Content Security Policy blocked frame navigation

CVE-2021-23968 4.3 - Medium - February 26, 2021

If Content Security Policy blocked frame navigation, the full destination of a redirect served in the frame was reported in the violation report; as opposed to the original frame URI. This could be used to leak sensitive information contained in such URIs. This vulnerability affects Firefox < 86, Thunderbird < 78.8, and Firefox ESR < 78.8.

Generation of Error Message Containing Sensitive Information

As specified in the W3C Content Security Policy draft, when creating a violation report, "User agents need to ensure

CVE-2021-23969 4.3 - Medium - February 26, 2021

As specified in the W3C Content Security Policy draft, when creating a violation report, "User agents need to ensure that the source file is the URL requested by the page, pre-redirects. If thats not possible, user agents need to strip the URL down to an origin to avoid unintentional leakage." Under certain types of redirects, Firefox incorrectly set the source file to be the destination of the redirects. This was fixed to be the redirect destination's origin. This vulnerability affects Firefox < 86, Thunderbird < 78.8, and Firefox ESR < 78.8.

Context-specific code was included in a shared jump table; resulting in assertions being triggered in multithreaded wasm code

CVE-2021-23970 6.5 - Medium - February 26, 2021

Context-specific code was included in a shared jump table; resulting in assertions being triggered in multithreaded wasm code. This vulnerability affects Firefox < 86.

assertion failure

When processing a redirect with a conflicting Referrer-Policy, Firefox would have adopted the redirect's Referrer-Policy

CVE-2021-23971 6.5 - Medium - February 26, 2021

When processing a redirect with a conflicting Referrer-Policy, Firefox would have adopted the redirect's Referrer-Policy. This would have potentially resulted in more information than intended by the original origin being provided to the destination of the redirect. This vulnerability affects Firefox < 86.

One phishing tactic on the web is to provide a link with HTTP Auth

CVE-2021-23972 8.8 - High - February 26, 2021

One phishing tactic on the web is to provide a link with HTTP Auth. For example 'https://www.phishingtarget.com@evil.com'. To mitigate this type of attack, Firefox will display a warning dialog; however, this warning dialog would not have been displayed if evil.com used a redirect that was cached by the browser. This vulnerability affects Firefox < 86.

When trying to load a cross-origin resource in an audio/video context a decoding error may have resulted, and the content of

CVE-2021-23973 6.5 - Medium - February 26, 2021

When trying to load a cross-origin resource in an audio/video context a decoding error may have resulted, and the content of that error may have revealed information about the resource. This vulnerability affects Firefox < 86, Thunderbird < 78.8, and Firefox ESR < 78.8.

Generation of Error Message Containing Sensitive Information

The DOMParser API did not properly process '<noscript>' elements for escaping

CVE-2021-23974 6.1 - Medium - February 26, 2021

The DOMParser API did not properly process '<noscript>' elements for escaping. This could be used as an mXSS vector to bypass an HTML Sanitizer. This vulnerability affects Firefox < 86.

The developer page about:memory has a Measure function for exploring what object types the browser has allocated and their sizes

CVE-2021-23975 6.5 - Medium - February 26, 2021

The developer page about:memory has a Measure function for exploring what object types the browser has allocated and their sizes. When this function was invoked we incorrectly called the sizeof function, instead of using the API method that checks for invalid pointers. This vulnerability affects Firefox < 86.

AuthZ

When accepting a malicious intent from other installed apps, Firefox for Android accepted manifests from arbitrary file paths and

CVE-2021-23976 8.1 - High - February 26, 2021

When accepting a malicious intent from other installed apps, Firefox for Android accepted manifests from arbitrary file paths and allowed declaring webapp manifests for other origins. This could be used to gain fullscreen access for UI spoofing and could also lead to cross-origin attacks on targeted websites. Note: This issue is a different issue from CVE-2020-26954 and only affected Firefox for Android. Other operating systems are unaffected. This vulnerability affects Firefox < 86.

Clickjacking

Side-channel information leakage in graphics in Google Chrome prior to 87.0.4280.66

CVE-2020-16012 4.3 - Medium - January 08, 2021

Side-channel information leakage in graphics in Google Chrome prior to 87.0.4280.66 allowed a remote attacker to leak cross-origin data via a crafted HTML page.

Certain blit values provided by the user were not properly constrained leading to a heap buffer overflow on some video drivers

CVE-2020-26971 8.8 - High - January 07, 2021

Certain blit values provided by the user were not properly constrained leading to a heap buffer overflow on some video drivers. This vulnerability affects Firefox < 84, Thunderbird < 78.6, and Firefox ESR < 78.6.

Memory Corruption

The lifecycle of IPC Actors allows managed actors to outlive their manager actors; and the former must ensure

CVE-2020-26972 9.8 - Critical - January 07, 2021

The lifecycle of IPC Actors allows managed actors to outlive their manager actors; and the former must ensure that they are not attempting to use a dead actor they have a reference to. Such a check was omitted in WebGL, resulting in a use-after-free and a potentially exploitable crash. This vulnerability affects Firefox < 84.

Dangling pointer

Certain input to the CSS Sanitizer confused it, resulting in incorrect components being removed

CVE-2020-26973 8.8 - High - January 07, 2021

Certain input to the CSS Sanitizer confused it, resulting in incorrect components being removed. This could have been used as a sanitizer bypass. This vulnerability affects Firefox < 84, Thunderbird < 78.6, and Firefox ESR < 78.6.

When flex-basis was used on a table wrapper, a StyleGenericFlexBasis object could have been incorrectly cast to the wrong type

CVE-2020-26974 8.8 - High - January 07, 2021

When flex-basis was used on a table wrapper, a StyleGenericFlexBasis object could have been incorrectly cast to the wrong type. This resulted in a heap user-after-free, memory corruption, and a potentially exploitable crash. This vulnerability affects Firefox < 84, Thunderbird < 78.6, and Firefox ESR < 78.6.

Memory Corruption

When a malicious application installed on the user's device broadcast an Intent to Firefox for Android

CVE-2020-26975 6.5 - Medium - January 07, 2021

When a malicious application installed on the user's device broadcast an Intent to Firefox for Android, arbitrary headers could have been specified, leading to attacks such as abusing ambient authority or session fixation. This was resolved by only allowing certain safe-listed headers. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 84.

When a HTTPS pages was embedded in a HTTP page

CVE-2020-26976 6.5 - Medium - January 07, 2021

When a HTTPS pages was embedded in a HTTP page, and there was a service worker registered for the former, the service worker could have intercepted the request for the secure page despite the iframe not being a secure context due to the (insecure) framing. This vulnerability affects Firefox < 84.

By attempting to connect a website using an unresponsive port

CVE-2020-26977 6.5 - Medium - January 07, 2021

By attempting to connect a website using an unresponsive port, an attacker could have controlled the content of a tab while the URL bar displayed the original domain. *Note: This issue only affects Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 84.

Using techniques that built on the slipstream research

CVE-2020-26978 6.1 - Medium - January 07, 2021

Using techniques that built on the slipstream research, a malicious webpage could have exposed both an internal network's hosts as well as services running on the user's local machine. This vulnerability affects Firefox < 84, Thunderbird < 78.6, and Firefox ESR < 78.6.

When a user typed a URL in the address bar or the search bar and quickly hit the enter key, a website could sometimes capture

CVE-2020-26979 6.1 - Medium - January 07, 2021

When a user typed a URL in the address bar or the search bar and quickly hit the enter key, a website could sometimes capture that event and then redirect the user before navigation occurred to the desired, entered address. To construct a convincing spoof the attacker would have had to guess what the user was typing, perhaps by suggesting it. This vulnerability affects Firefox < 84.

Open Redirect

When an extension with the proxy permission registered to receive <all_urls>

CVE-2020-35111 4.3 - Medium - January 07, 2021

When an extension with the proxy permission registered to receive <all_urls>, the proxy.onRequest callback was not triggered for view-source URLs. While web content cannot navigate to such URLs, a user opening View Source could have inadvertently leaked their IP address. This vulnerability affects Firefox < 84, Thunderbird < 78.6, and Firefox ESR < 78.6.

Mozilla developers reported memory safety bugs present in Firefox 83 and Firefox ESR 78.5

CVE-2020-35113 8.8 - High - January 07, 2021

Mozilla developers reported memory safety bugs present in Firefox 83 and Firefox ESR 78.5. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 84, Thunderbird < 78.6, and Firefox ESR < 78.6.

Memory Corruption

Mozilla developers reported memory safety bugs present in Firefox 83

CVE-2020-35114 8.8 - High - January 07, 2021

Mozilla developers reported memory safety bugs present in Firefox 83. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 84.

Memory Corruption

In certain circumstances, the MCallGetProperty opcode

CVE-2020-26950 8.8 - High - December 09, 2020

In certain circumstances, the MCallGetProperty opcode can be emitted with unmet assumptions resulting in an exploitable use-after-free condition. This vulnerability affects Firefox < 82.0.3, Firefox ESR < 78.4.1, and Thunderbird < 78.4.2.

Dangling pointer

A parsing and event loading mismatch in Firefox's SVG code could have allowed load events to fire, even after sanitization

CVE-2020-26951 6.1 - Medium - December 09, 2020

A parsing and event loading mismatch in Firefox's SVG code could have allowed load events to fire, even after sanitization. An attacker already capable of exploiting an XSS vulnerability in privileged internal pages could have used this attack to bypass our built-in sanitizer. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

XSS

Incorrect bookkeeping of functions inlined during JIT compilation could have led to memory corruption and a potentially exploitable crash when handling out-of-memory errors

CVE-2020-26952 8.8 - High - December 09, 2020

Incorrect bookkeeping of functions inlined during JIT compilation could have led to memory corruption and a potentially exploitable crash when handling out-of-memory errors. This vulnerability affects Firefox < 83.

Memory Corruption

It was possible to cause the browser to enter fullscreen mode without displaying the security UI; thus making it possible to attempt a phishing attack or otherwise confuse the user

CVE-2020-26953 4.3 - Medium - December 09, 2020

It was possible to cause the browser to enter fullscreen mode without displaying the security UI; thus making it possible to attempt a phishing attack or otherwise confuse the user. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

Clickjacking

When accepting a malicious intent from other installed apps, Firefox for Android accepted manifests from arbitrary file paths and

CVE-2020-26954 4.3 - Medium - December 09, 2020

When accepting a malicious intent from other installed apps, Firefox for Android accepted manifests from arbitrary file paths and allowed declaring webapp manifests for other origins. This could be used to gain fullscreen access for UI spoofing and could also lead to cross-origin attacks on targeted websites. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 83.

When a user downloaded a file in Firefox for Android, if a cookie is set, it

CVE-2020-26955 6.5 - Medium - December 09, 2020

When a user downloaded a file in Firefox for Android, if a cookie is set, it would have been re-sent during a subsequent file download operation on the same domain, regardless of whether the original and subsequent request were in private and non-private browsing modes. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 83.

Reliance on Cookies without Validation and Integrity Checking

In some cases, removing HTML elements during sanitization would keep existing SVG event handlers and therefore lead to XSS

CVE-2020-26956 6.1 - Medium - December 09, 2020

In some cases, removing HTML elements during sanitization would keep existing SVG event handlers and therefore lead to XSS. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

XSS

OneCRL was non-functional in the new Firefox for Android due to a missing service initialization

CVE-2020-26957 6.5 - Medium - December 09, 2020

OneCRL was non-functional in the new Firefox for Android due to a missing service initialization. This could result in a failure to enforce some certificate revocations. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 83.

Improper Initialization

Firefox did not block execution of scripts with incorrect MIME types when the response was intercepted and cached through a ServiceWorker

CVE-2020-26958 6.1 - Medium - December 09, 2020

Firefox did not block execution of scripts with incorrect MIME types when the response was intercepted and cached through a ServiceWorker. This could lead to a cross-site script inclusion vulnerability, or a Content Security Policy bypass. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

XSS

During browser shutdown

CVE-2020-26959 8.8 - High - December 09, 2020

During browser shutdown, reference decrementing could have occured on a previously freed object, resulting in a use-after-free, memory corruption, and a potentially exploitable crash. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

Dangling pointer

If the Compact() method was called on an nsTArray

CVE-2020-26960 8.8 - High - December 09, 2020

If the Compact() method was called on an nsTArray, the array could have been reallocated without updating other pointers, leading to a potential use-after-free and exploitable crash. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

Dangling pointer

When DNS over HTTPS is in use, it intentionally filters RFC1918 and related IP ranges

CVE-2020-26961 6.5 - Medium - December 09, 2020

When DNS over HTTPS is in use, it intentionally filters RFC1918 and related IP ranges from the responses as these do not make sense coming from a DoH resolver. However when an IPv4 address was mapped through IPv6, these addresses were erroneously let through, leading to a potential DNS Rebinding attack. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

Cross-origin iframes that contained a login form could have been recognized by the login autofill service, and populated

CVE-2020-26962 6.1 - Medium - December 09, 2020

Cross-origin iframes that contained a login form could have been recognized by the login autofill service, and populated. This could have been used in clickjacking attacks, as well as be read across partitions in dynamic first party isolation. This vulnerability affects Firefox < 83.

Clickjacking

Repeated calls to the history and location interfaces could have been used to hang the browser

CVE-2020-26963 4.3 - Medium - December 09, 2020

Repeated calls to the history and location interfaces could have been used to hang the browser. This was addressed by introducing rate-limiting to these API calls. This vulnerability affects Firefox < 83.

Some websites have a feature "Show Password" where clicking a button will change a password field into a textbook field

CVE-2020-26965 6.5 - Medium - December 09, 2020

Some websites have a feature "Show Password" where clicking a button will change a password field into a textbook field, revealing the typed password. If, when using a software keyboard that remembers user input, a user typed their password and used that feature, the type of the password field was changed, resulting in a keyboard layout change and the possibility for the software keyboard to remember the typed password. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

Improper Removal of Sensitive Information Before Storage or Transfer

When listening for page changes with a Mutation Observer, a malicious web page could confuse Firefox Screenshots into interacting with elements other than those

CVE-2020-26967 6.5 - Medium - December 09, 2020

When listening for page changes with a Mutation Observer, a malicious web page could confuse Firefox Screenshots into interacting with elements other than those that it injected into the page. This would lead to internal errors and unexpected behavior in the Screenshots code. This vulnerability affects Firefox < 83.

Mozilla developers reported memory safety bugs present in Firefox 82 and Firefox ESR 78.4

CVE-2020-26968 8.8 - High - December 09, 2020

Mozilla developers reported memory safety bugs present in Firefox 82 and Firefox ESR 78.4. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

Memory Corruption

Mozilla developers reported memory safety bugs present in Firefox 82

CVE-2020-26969 8.8 - High - December 09, 2020

Mozilla developers reported memory safety bugs present in Firefox 82. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 83.

Memory Corruption

When performing EC scalar point multiplication, the wNAF point multiplication algorithm was used;

CVE-2020-6829 5.3 - Medium - October 28, 2020

When performing EC scalar point multiplication, the wNAF point multiplication algorithm was used; which leaked partial information about the nonce used during signature generation. Given an electro-magnetic trace of a few signature generations, the private key could have been computed. This vulnerability affects Firefox < 80 and Firefox for Android < 80.

If a valid external protocol handler was referenced in an image tag, the resulting broken image size could be distinguished

CVE-2020-15680 5.3 - Medium - October 22, 2020

If a valid external protocol handler was referenced in an image tag, the resulting broken image size could be distinguished from a broken image size of a non-existent protocol handler. This allowed an attacker to successfully probe whether an external protocol handler was registered. This vulnerability affects Firefox < 82.

When multiple WASM threads had a reference to a module

CVE-2020-15681 7.5 - High - October 22, 2020

When multiple WASM threads had a reference to a module, and were looking up exported functions, one WASM thread could have overwritten another's entry in a shared stub table, resulting in a potentially exploitable crash. This vulnerability affects Firefox < 82.

When a link to an external protocol was clicked, a prompt was presented that allowed the user to choose what application to open it in

CVE-2020-15682 6.5 - Medium - October 22, 2020

When a link to an external protocol was clicked, a prompt was presented that allowed the user to choose what application to open it in. An attacker could induce that prompt to be associated with an origin they didn't control, resulting in a spoofing attack. This was fixed by changing external protocol prompts to be tab-modal while also ensuring they could not be incorrectly associated with a different origin. This vulnerability affects Firefox < 82.

Origin Validation Error

Mozilla developers and community members reported memory safety bugs present in Firefox 81 and Firefox ESR 78.3

CVE-2020-15683 9.8 - Critical - October 22, 2020

Mozilla developers and community members reported memory safety bugs present in Firefox 81 and Firefox ESR 78.3. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox ESR < 78.4, Firefox < 82, and Thunderbird < 78.4.

Mozilla developers reported memory safety bugs present in Firefox 81

CVE-2020-15684 9.8 - Critical - October 22, 2020

Mozilla developers reported memory safety bugs present in Firefox 81. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 82.

When converting coordinates

CVE-2020-12400 4.7 - Medium - October 08, 2020

When converting coordinates from projective to affine, the modular inversion was not performed in constant time, resulting in a possible timing-based side channel attack. This vulnerability affects Firefox < 80 and Firefox for Android < 80.

Information Disclosure

During ECDSA signature generation

CVE-2020-12401 4.7 - Medium - October 08, 2020

During ECDSA signature generation, padding applied in the nonce designed to ensure constant-time scalar multiplication was removed, resulting in variable-time execution dependent on secret data. This vulnerability affects Firefox < 80 and Firefox for Android < 80.

Use of a Broken or Risky Cryptographic Algorithm

If Firefox is installed to a user-writable directory, the Mozilla Maintenance Service would execute updater.exe

CVE-2020-15663 8.8 - High - October 01, 2020

If Firefox is installed to a user-writable directory, the Mozilla Maintenance Service would execute updater.exe from the install location with system privileges. Although the Mozilla Maintenance Service does ensure that updater.exe is signed by Mozilla, the version could have been rolled back to a previous version which would have allowed exploitation of an older bug and arbitrary code execution with System Privileges. *Note: This issue only affected Windows operating systems. Other operating systems are unaffected.*. This vulnerability affects Firefox < 80, Thunderbird < 78.2, Thunderbird < 68.12, Firefox ESR < 68.12, and Firefox ESR < 78.2.

Improper Privilege Management

By holding a reference to the eval() function from an about:blank window, a malicious webpage could have gained access to the InstallTrigger object which would

CVE-2020-15664 6.5 - Medium - October 01, 2020

By holding a reference to the eval() function from an about:blank window, a malicious webpage could have gained access to the InstallTrigger object which would allow them to prompt the user to install an extension. Combined with user confusion, this could result in an unintended or malicious extension being installed. This vulnerability affects Firefox < 80, Thunderbird < 78.2, Thunderbird < 68.12, Firefox ESR < 68.12, Firefox ESR < 78.2, and Firefox for Android < 80.

AuthZ

Firefox did not reset the address bar after the beforeunload dialog was shown if the user chose to remain on the page

CVE-2020-15665 4.3 - Medium - October 01, 2020

Firefox did not reset the address bar after the beforeunload dialog was shown if the user chose to remain on the page. This could have resulted in an incorrect URL being shown when used in conjunction with other unexpected browser behaviors. This vulnerability affects Firefox < 80.

When trying to load a non-video in an audio/video context the exact status code (200, 302, 404, 500, 412, 403, etc

CVE-2020-15666 6.5 - Medium - October 01, 2020

When trying to load a non-video in an audio/video context the exact status code (200, 302, 404, 500, 412, 403, etc.) was disclosed via the MediaError Message. This level of information leakage is inconsistent with the standardized onerror/onsuccess disclosure and can lead to inferring login status to services or device discovery on a local network among other attacks. This vulnerability affects Firefox < 80 and Firefox for Android < 80.

Information Disclosure

When processing a MAR update file

CVE-2020-15667 8.8 - High - October 01, 2020

When processing a MAR update file, after the signature has been validated, an invalid name length could result in a heap overflow, leading to memory corruption and potentially arbitrary code execution. Within Firefox as released by Mozilla, this issue is only exploitable with the Mozilla-controlled signing key. This vulnerability affects Firefox < 80.

Unrestricted File Upload

A lock was missing when accessing a data structure and importing certificate information into the trust database

CVE-2020-15668 4.3 - Medium - October 01, 2020

A lock was missing when accessing a data structure and importing certificate information into the trust database. This vulnerability affects Firefox < 80 and Firefox for Android < 80.

Improper Locking

Mozilla developers reported memory safety bugs present in Firefox for Android 79

CVE-2020-15670 8.8 - High - October 01, 2020

Mozilla developers reported memory safety bugs present in Firefox for Android 79. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 80, Firefox ESR < 78.2, Thunderbird < 78.2, and Firefox for Android < 80.

Release of Invalid Pointer or Reference

When typing in a password under certain conditions

CVE-2020-15671 3.1 - Low - October 01, 2020

When typing in a password under certain conditions, a race may have occured where the InputContext was not being correctly set for the input field, resulting in the typed password being saved to the keyboard dictionary. This vulnerability affects Firefox for Android < 80.

Improper Input Validation

Mozilla developers reported memory safety bugs present in Firefox 80 and Firefox ESR 78.2

CVE-2020-15673 8.8 - High - October 01, 2020

Mozilla developers reported memory safety bugs present in Firefox 80 and Firefox ESR 78.2. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 81, Thunderbird < 78.3, and Firefox ESR < 78.3.

Release of Invalid Pointer or Reference

Mozilla developers reported memory safety bugs present in Firefox 80

CVE-2020-15674 8.8 - High - October 01, 2020

Mozilla developers reported memory safety bugs present in Firefox 80. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 81.

Release of Invalid Pointer or Reference

When processing surfaces, the lifetime may outlive a persistent buffer leading to memory corruption and a potentially exploitable crash

CVE-2020-15675 8.8 - High - October 01, 2020

When processing surfaces, the lifetime may outlive a persistent buffer leading to memory corruption and a potentially exploitable crash. This vulnerability affects Firefox < 81.

Classic Buffer Overflow

Firefox sometimes ran the onload handler for SVG elements

CVE-2020-15676 6.1 - Medium - October 01, 2020

Firefox sometimes ran the onload handler for SVG elements that the DOM sanitizer decided to remove, resulting in JavaScript being executed after pasting attacker-controlled data into a contenteditable element. This vulnerability affects Firefox < 81, Thunderbird < 78.3, and Firefox ESR < 78.3.

XSS

By exploiting an Open Redirect vulnerability on a website, an attacker could have spoofed the site displayed in the download file dialog to show the original site (the one suffering

CVE-2020-15677 6.1 - Medium - October 01, 2020

By exploiting an Open Redirect vulnerability on a website, an attacker could have spoofed the site displayed in the download file dialog to show the original site (the one suffering from the open redirect) rather than the site the file was actually downloaded from. This vulnerability affects Firefox < 81, Thunderbird < 78.3, and Firefox ESR < 78.3.

Open Redirect

When recursing through graphical layers while scrolling, an iterator may have become invalid, resulting in a potential use-after-free

CVE-2020-15678 8.8 - High - October 01, 2020

When recursing through graphical layers while scrolling, an iterator may have become invalid, resulting in a potential use-after-free. This occurs because the function APZCTreeManager::ComputeClippedCompositionBounds did not follow iterator invalidation rules. This vulnerability affects Firefox < 81, Thunderbird < 78.3, and Firefox ESR < 78.3.

Dangling pointer

Using object or embed tags, it was possible to frame other websites, even if they disallowed framing using the X-Frame-Options header

CVE-2020-15648 6.5 - Medium - August 10, 2020

Using object or embed tags, it was possible to frame other websites, even if they disallowed framing using the X-Frame-Options header. This vulnerability affects Thunderbird < 78 and Firefox < 78.0.2.

Clickjacking

By observing the stack trace for JavaScript errors in web workers, it was possible to leak the result of a cross-origin redirect

CVE-2020-15652 6.5 - Medium - August 10, 2020

By observing the stack trace for JavaScript errors in web workers, it was possible to leak the result of a cross-origin redirect. This applied only to content that can be parsed as script. This vulnerability affects Firefox < 79, Firefox ESR < 68.11, Firefox ESR < 78.1, Thunderbird < 68.11, and Thunderbird < 78.1.

Origin Validation Error

An iframe sandbox element with the allow-popups flag could be bypassed when using noopener links

CVE-2020-15653 6.5 - Medium - August 10, 2020

An iframe sandbox element with the allow-popups flag could be bypassed when using noopener links. This could have led to security issues for websites relying on sandbox configurations that allowed popups and hosted arbitrary content. This vulnerability affects Firefox ESR < 78.1, Firefox < 79, and Thunderbird < 78.1.

When in an endless loop

CVE-2020-15654 6.5 - Medium - August 10, 2020

When in an endless loop, a website specifying a custom cursor using CSS could make it look like the user is interacting with the user interface, when they are not. This could lead to a perceived broken state, especially when interactions with existing browser dialogs and warnings do not work. This vulnerability affects Firefox ESR < 78.1, Firefox < 79, and Thunderbird < 78.1.

Infinite Loop

A redirected HTTP request

CVE-2020-15655 6.5 - Medium - August 10, 2020

A redirected HTTP request which is observed or modified through a web extension could bypass existing CORS checks, leading to potential disclosure of cross-origin information. This vulnerability affects Firefox ESR < 78.1, Firefox < 79, and Thunderbird < 78.1.

Information Disclosure

JIT optimizations involving the Javascript arguments object could confuse later optimizations

CVE-2020-15656 8.8 - High - August 10, 2020

JIT optimizations involving the Javascript arguments object could confuse later optimizations. This risk was already mitigated by various precautions in the code, resulting in this bug rated at only moderate severity. This vulnerability affects Firefox ESR < 78.1, Firefox < 79, and Thunderbird < 78.1.

Object Type Confusion

The code for downloading files did not properly take care of special characters

CVE-2020-15658 6.5 - Medium - August 10, 2020

The code for downloading files did not properly take care of special characters, which led to an attacker being able to cut off the file ending at an earlier position, leading to a different file type being downloaded than shown in the dialog. This vulnerability affects Firefox ESR < 78.1, Firefox < 79, and Thunderbird < 78.1.

Improper Check for Unusual or Exceptional Conditions

Mozilla developers and community members reported memory safety bugs present in Firefox 78 and Firefox ESR 78.0

CVE-2020-15659 8.8 - High - August 10, 2020

Mozilla developers and community members reported memory safety bugs present in Firefox 78 and Firefox ESR 78.0. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 79, Firefox ESR < 68.11, Firefox ESR < 78.1, Thunderbird < 68.11, and Thunderbird < 78.1.

Memory Corruption

NSS has shown timing differences when performing DSA signatures, which was exploitable and could eventually leak private keys

CVE-2020-12399 4.4 - Medium - July 09, 2020

NSS has shown timing differences when performing DSA signatures, which was exploitable and could eventually leak private keys. This vulnerability affects Thunderbird < 68.9.0, Firefox < 77, and Firefox ESR < 68.9.

Side Channel Attack

During RSA key generation, bignum implementations used a variation of the Binary Extended Euclidean Algorithm

CVE-2020-12402 4.4 - Medium - July 09, 2020

During RSA key generation, bignum implementations used a variation of the Binary Extended Euclidean Algorithm which entailed significantly input-dependent flow. This allowed an attacker able to perform electromagnetic-based side channel attacks to record traces leading to the recovery of the secret primes. *Note:* An unmodified Firefox browser does not generate RSA keys in normal operation and is not affected, but products built on top of it might. This vulnerability affects Firefox < 78.

Use of a Broken or Risky Cryptographic Algorithm

When browsing a malicious page, a race condition in our SharedWorkerService could occur and lead to a potentially exploitable crash

CVE-2020-12405 5.3 - Medium - July 09, 2020

When browsing a malicious page, a race condition in our SharedWorkerService could occur and lead to a potentially exploitable crash. This vulnerability affects Thunderbird < 68.9.0, Firefox < 77, and Firefox ESR < 68.9.

Dangling pointer

Mozilla Developer Iain Ireland discovered a missing type check during unboxed objects removal, resulting in a crash

CVE-2020-12406 8.8 - High - July 09, 2020

Mozilla Developer Iain Ireland discovered a missing type check during unboxed objects removal, resulting in a crash. We presume that with enough effort that it could be exploited to run arbitrary code. This vulnerability affects Thunderbird < 68.9.0, Firefox < 77, and Firefox ESR < 68.9.

Insufficient Verification of Data Authenticity

Mozilla Developer Nicolas Silva found

CVE-2020-12407 6.5 - Medium - July 09, 2020

Mozilla Developer Nicolas Silva found that when using WebRender, Firefox would under certain conditions leak arbitrary GPU memory to the visible screen. The leaked memory content was visible to the user, but not observable from web content. This vulnerability affects Firefox < 77.

Information Disclosure

When browsing a document hosted on an IP address

CVE-2020-12408 6.5 - Medium - July 09, 2020

When browsing a document hosted on an IP address, an attacker could insert certain characters to flip domain and path information in the address bar. This vulnerability affects Firefox < 77.

Injection

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