Firefox Mozilla Firefox Open source web browser

Do you want an email whenever new security vulnerabilities are reported in Mozilla Firefox?

Recent Mozilla Firefox Security Advisories

Advisory Title Published
mfsa2021-43 Security Vulnerabilities fixed in Firefox 93 mfsa2021-43 October 5, 2021
mfsa2021-45 Security Vulnerabilities fixed in Firefox ESR 91.2 mfsa2021-45 October 5, 2021
mfsa2021-44 Security Vulnerabilities fixed in Firefox ESR 78.15 mfsa2021-44 October 5, 2021
mfsa2021-38 Security Vulnerabilities fixed in Firefox 92 mfsa2021-38 September 7, 2021
mfsa2021-39 Security Vulnerabilities fixed in Firefox ESR 78.14 mfsa2021-39 September 7, 2021
mfsa2021-40 Security Vulnerabilities fixed in Firefox ESR 91.1 mfsa2021-40 September 7, 2021
mfsa2021-37 Security Vulnerabilities fixed in Firefox 91.0.1 and Thunderbird 91.0.1 mfsa2021-37 August 16, 2021
mfsa2021-34 Security Vulnerabilities fixed in Firefox ESR 78.13 mfsa2021-34 August 10, 2021
mfsa2021-33 Security Vulnerabilities fixed in Firefox 91 mfsa2021-33 August 10, 2021
mfsa2021-28 Security Vulnerabilities fixed in Firefox 90 mfsa2021-28 July 13, 2021

@firefox Tweets

Trackers can be like zombies following your every move �� Thankfully, these anti-tracking browser extensions make… https://t.co/xolu60b9et
Fri Oct 22 21:51:00 +0000 2021

New favorite account. https://t.co/Ps6WMdqJ8H
Thu Oct 21 18:31:07 +0000 2021

By the Year

In 2021 there have been 89 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 0.25

Year Vulnerabilities Average Score
2021 89 7.11
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

Uninitialized memory in a

CVE-2021-29980 8.8 - High - August 17, 2021

Uninitialized memory in a canvas object could have caused an incorrect free() leading to memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 78.13, Thunderbird < 91, Firefox ESR < 78.13, and Firefox < 91.

Missing Initialization of Resource

Firefox incorrectly treated an inline list-item element as a block element

CVE-2021-29988 8.8 - High - August 17, 2021

Firefox incorrectly treated an inline list-item element as a block element, resulting in an out of bounds read or memory corruption, and a potentially exploitable crash. This vulnerability affects Thunderbird < 78.13, Thunderbird < 91, Firefox ESR < 78.13, and Firefox < 91.

Interpretation Conflict

A use-after-free vulnerability in media channels could have led to memory corruption and a potentially exploitable crash

CVE-2021-29985 8.8 - High - August 17, 2021

A use-after-free vulnerability in media channels could have led to memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 78.13, Thunderbird < 91, Firefox ESR < 78.13, and Firefox < 91.

Dangling pointer

Instruction reordering resulted in a sequence of instructions

CVE-2021-29984 8.8 - High - August 17, 2021

Instruction reordering resulted in a sequence of instructions that would cause an object to be incorrectly considered during garbage collection. This led to memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 78.13, Thunderbird < 91, Firefox ESR < 78.13, and Firefox < 91.

Due to incorrect JIT optimization, we incorrectly interpreted data

CVE-2021-29982 6.5 - Medium - August 17, 2021

Due to incorrect JIT optimization, we incorrectly interpreted data from the wrong type of object, resulting in the potential leak of a single bit of memory. This vulnerability affects Firefox < 91 and Thunderbird < 91.

Missing Release of Resource after Effective Lifetime

An issue present in lowering/register allocation could have led to obscure but deterministic register confusion failures in JITted code

CVE-2021-29981 8.8 - High - August 17, 2021

An issue present in lowering/register allocation could have led to obscure but deterministic register confusion failures in JITted code that would lead to a potentially exploitable crash. This vulnerability affects Firefox < 91 and Thunderbird < 91.

Mozilla developers and community members reported memory safety bugs present in Firefox 90

CVE-2021-29990 8.8 - High - August 17, 2021

Mozilla developers and community members reported memory safety bugs present in Firefox 90. 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 < 91.

Buffer Overflow

Mozilla developers reported memory safety bugs present in Firefox 90 and Firefox ESR 78.12

CVE-2021-29989 8.8 - High - August 17, 2021

Mozilla developers reported memory safety bugs present in Firefox 90 and Firefox ESR 78.12. 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 Thunderbird < 78.13, Firefox ESR < 78.13, and Firefox < 91.

Buffer Overflow

Mozilla developers reported memory safety bugs present in Firefox 89

CVE-2021-29977 8.8 - High - August 05, 2021

Mozilla developers reported memory safety bugs present in Firefox 89. 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 < 90.

Memory Corruption

Mozilla developers reported memory safety bugs present in code shared between Firefox and Thunderbird

CVE-2021-29976 8.8 - High - August 05, 2021

Mozilla developers reported memory safety bugs present in code shared between Firefox and Thunderbird. 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 Thunderbird < 78.12, Firefox ESR < 78.12, and Firefox < 90.

Memory Corruption

Through a series of DOM manipulations, a message, over

CVE-2021-29975 6.5 - Medium - August 05, 2021

Through a series of DOM manipulations, a message, over which the attacker had control of the text but not HTML or formatting, could be overlaid on top of another domain (with the new domain correctly shown in the address bar) resulting in possible user confusion. This vulnerability affects Firefox < 90.

When network partitioning was enabled, e.g

CVE-2021-29974 4.3 - Medium - August 05, 2021

When network partitioning was enabled, e.g. as a result of Enhanced Tracking Protection settings, a TLS error page would allow the user to override an error on a domain which had specified HTTP Strict Transport Security (which implies that the error should not be override-able.) This issue did not affect the network connections, and they were correctly upgraded to HTTPS automatically. This vulnerability affects Firefox < 90.

Password autofill was enabled without user interaction on insecure websites on Firefox for Android

CVE-2021-29973 8.8 - High - August 05, 2021

Password autofill was enabled without user interaction on insecure websites on Firefox for Android. This was corrected to require user interaction with the page before a user's password would be entered by the browser's autofill functionality *This bug only affects Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 90.

A use-after-free vulnerability was found via testing, and traced to an out-of-date Cairo library

CVE-2021-29972 8.8 - High - August 05, 2021

A use-after-free vulnerability was found via testing, and traced to an out-of-date Cairo library. Updating the library resolved the issue, and may have remediated other, unknown security vulnerabilities as well. This vulnerability affects Firefox < 90.

Dangling pointer

If a user had granted a permission to a webpage and saved

CVE-2021-29971 9.8 - Critical - August 05, 2021

If a user had granted a permission to a webpage and saved that grant, any webpage running on the same host - irrespective of scheme or port - would be granted that permission. *This bug only affects Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 90.

Improper Preservation of Permissions

A malicious webpage could have triggered a use-after-free, memory corruption, and a potentially exploitable crash

CVE-2021-29970 8.8 - High - August 05, 2021

A malicious webpage could have triggered a use-after-free, memory corruption, and a potentially exploitable crash. *This bug could only be triggered when accessibility was enabled.*. This vulnerability affects Thunderbird < 78.12, Firefox ESR < 78.12, and Firefox < 90.

Dangling pointer

Mozilla developers reported memory safety bugs present in Firefox 88 and Firefox ESR 78.11

CVE-2021-29967 8.8 - High - June 24, 2021

Mozilla developers reported memory safety bugs present in Firefox 88 and Firefox ESR 78.11. 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 Thunderbird < 78.11, Firefox < 89, and Firefox ESR < 78.11.

Buffer Overflow

Mozilla developers reported memory safety bugs present in Firefox 88

CVE-2021-29966 8.8 - High - June 24, 2021

Mozilla developers reported memory safety bugs present in Firefox 88. 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 < 89.

Buffer Overflow

Firefox for Android would become unstable and hard-to-recover when a website opened too many popups

CVE-2021-29962 4.3 - Medium - June 24, 2021

Firefox for Android would become unstable and hard-to-recover when a website opened too many popups. *This bug only affects Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 89.

Improper Resource Shutdown or Release

When a download was initiated, the client did not check whether it was in normal or private browsing mode

CVE-2021-29958 4.3 - Medium - June 24, 2021

When a download was initiated, the client did not check whether it was in normal or private browsing mode, which led to private mode cookies being shared in normal browsing mode. This vulnerability affects Firefox for iOS < 34.

Exposure of Resource to Wrong Sphere

When Web Render components were destructed, a race condition could have caused undefined behavior, and we presume

CVE-2021-29952 7.5 - High - June 24, 2021

When Web Render components were destructed, a race condition could have caused undefined behavior, and we presume that with enough effort may have been exploitable to run arbitrary code. This vulnerability affects Firefox < 88.0.1 and Firefox for Android < 88.1.3.

Race Condition

Mozilla developers and community members reported memory safety bugs present in Firefox 87

CVE-2021-29947 8.8 - High - June 24, 2021

Mozilla developers and community members reported memory safety bugs present in Firefox 87. 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 < 88.

Buffer Overflow

Ports that were written as an integer overflow above the bounds of a 16-bit integer could have bypassed port blocking restrictions when used in the Alt-Svc header

CVE-2021-29946 8.8 - High - June 24, 2021

Ports that were written as an integer overflow above the bounds of a 16-bit integer could have bypassed port blocking restrictions when used in the Alt-Svc header. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

Integer Overflow or Wraparound

Firefox used to cache the last filename used for printing a file

CVE-2021-29960 4.3 - Medium - June 24, 2021

Firefox used to cache the last filename used for printing a file. When generating a filename for printing, Firefox usually suggests the web page title. The caching and suggestion techniques combined may have lead to the title of a website visited during private browsing mode being stored on disk. This vulnerability affects Firefox < 89.

Incorrect Resource Transfer Between Spheres

When a user has already

CVE-2021-29959 4.3 - Medium - June 24, 2021

When a user has already allowed a website to access microphone and camera, disabling camera sharing would not fully prevent the website from re-enabling it without an additional prompt. This was only possible if the website kept recording with the microphone until re-enabling the camera. This vulnerability affects Firefox < 89.

AuthZ

A transient execution vulnerability, named Floating Point Value Injection (FPVI)

CVE-2021-29955 5.3 - Medium - June 24, 2021

A transient execution vulnerability, named Floating Point Value Injection (FPVI) allowed an attacker to leak arbitrary memory addresses and may have also enabled JIT type confusion attacks. (A related vulnerability, Speculative Code Store Bypass (SCSB), did not affect Firefox.). This vulnerability affects Firefox ESR < 78.9 and Firefox < 87.

Injection

A malicious webpage could have forced a Firefox for Android user into executing attacker-controlled JavaScript in the context of another domain

CVE-2021-29953 6.1 - Medium - June 24, 2021

A malicious webpage could have forced a Firefox for Android user into executing attacker-controlled JavaScript in the context of another domain, resulting in a Universal Cross-Site Scripting vulnerability. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected. Further details are being temporarily withheld to allow users an opportunity to update.*. This vulnerability affects Firefox < 88.0.1 and Firefox for Android < 88.1.3.

XSS

The WebAssembly JIT could miscalculate the size of a return type, which could lead to a null read and result in a crash

CVE-2021-29945 6.5 - Medium - June 24, 2021

The WebAssembly JIT could miscalculate the size of a return type, which could lead to a null read and result in a crash. *Note: This issue only affected x86-32 platforms. Other platforms are unaffected.*. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

Incorrect Calculation

A malicious website

CVE-2021-29965 5.3 - Medium - June 24, 2021

A malicious website that causes an HTTP Authentication dialog to be spawned could trick the built-in password manager to suggest passwords for the currently active website instead of the website that triggered the dialog. *This bug only affects Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 89.

Externally Controlled Reference to a Resource in Another Sphere

When styling and rendering an oversized `<select>` element, Firefox did not apply correct clipping which

CVE-2021-29961 4.3 - Medium - June 24, 2021

When styling and rendering an oversized `<select>` element, Firefox did not apply correct clipping which allowed an attacker to paint over the user interface. This vulnerability affects Firefox < 89.

AuthZ

Address bar search suggestions in private browsing mode were re-using session data from normal mode

CVE-2021-29963 4.3 - Medium - June 24, 2021

Address bar search suggestions in private browsing mode were re-using session data from normal mode. *This bug only affects Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 89.

Insufficient Verification of Data Authenticity

A race condition with requestPointerLock() and setTimeout() could have resulted in a user interacting with one tab when they believed they were on a separate tab

CVE-2021-24000 3.1 - Low - June 24, 2021

A race condition with requestPointerLock() and setTimeout() could have resulted in a user interacting with one tab when they believed they were on a separate tab. In conjunction with certain elements (such as &lt;input type="file"&gt;) this could have led to an attack where a user was confused about the origin of the webpage and potentially disclosed information they did not intend to. This vulnerability affects Firefox < 88.

Lack of escaping allowed HTML injection when a webpage was viewed in Reader View

CVE-2021-29944 6.1 - Medium - June 24, 2021

Lack of escaping allowed HTML injection when a webpage was viewed in Reader View. While a Content Security Policy prevents direct code execution, HTML injection is still possible. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 88.

XSS

When a user clicked on an FTP URL containing encoded newline characters (%0A and %0D), the newlines would have been interpreted as such and

CVE-2021-24002 8.8 - High - June 24, 2021

When a user clicked on an FTP URL containing encoded newline characters (%0A and %0D), the newlines would have been interpreted as such and allowed arbitrary commands to be sent to the FTP server. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

Argument Injection

A compromised content process could have performed session history manipulations it should not have been able to due to testing infrastructure

CVE-2021-24001 4.3 - Medium - June 24, 2021

A compromised content process could have performed session history manipulations it should not have been able to due to testing infrastructure that was not restricted to testing-only configurations. This vulnerability affects Firefox < 88.

Exposure of Resource to Wrong Sphere

If a Blob URL was loaded through some unusual user interaction, it could have been loaded by the System Principal and granted additional privileges

CVE-2021-23999 8.8 - High - June 24, 2021

If a Blob URL was loaded through some unusual user interaction, it could have been loaded by the System Principal and granted additional privileges that should not be granted to web content. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

Improper Privilege Management

Through complicated navigations with new windows, an HTTP page could have inherited a secure lock icon from an HTTPS page

CVE-2021-23998 6.5 - Medium - June 24, 2021

Through complicated navigations with new windows, an HTTP page could have inherited a secure lock icon from an HTTPS page. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

Insufficient Verification of Data Authenticity

Due to unexpected data type conversions, a use-after-free could have occurred when interacting with the font cache

CVE-2021-23997 8.8 - High - June 24, 2021

Due to unexpected data type conversions, a use-after-free could have occurred when interacting with the font cache. We presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability affects Firefox < 88.

Incorrect Conversion between Numeric Types

By utilizing 3D CSS in conjunction with Javascript, content could have been rendered outside the webpage's viewport, resulting in a spoofing attack

CVE-2021-23996 6.5 - Medium - June 24, 2021

By utilizing 3D CSS in conjunction with Javascript, content could have been rendered outside the webpage's viewport, resulting in a spoofing attack that could have been used for phishing or other attacks on a user. This vulnerability affects Firefox < 88.

When Responsive Design Mode was enabled, it used references to objects that were previously freed

CVE-2021-23995 8.8 - High - June 24, 2021

When Responsive Design Mode was enabled, it used references to objects that were previously freed. We presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

Operation on a Resource after Expiration or Release

A WebGL framebuffer was not initialized early enough, resulting in memory corruption and an out of bound write

CVE-2021-23994 8.8 - High - June 24, 2021

A WebGL framebuffer was not initialized early enough, resulting in memory corruption and an out of bound write. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

Missing Initialization of Resource

Cross-site scripting (XSS) vulnerability in Mozilla Firefox before 3.6.24 and 4.x through 7

CVE-2011-3656 6.1 - Medium - June 02, 2021

Cross-site scripting (XSS) vulnerability in Mozilla Firefox before 3.6.24 and 4.x through 7 allows remote attackers to inject arbitrary web script or HTML via vectors involving HTTP 0.9 errors, non-default ports, and content-sniffing.

XSS

A flaw in Mozilla's embedded certificate code might

CVE-2007-5967 6.5 - Medium - May 17, 2021

A flaw in Mozilla's embedded certificate code might allow web sites to install root certificates on devices without user approval.

Improper Certificate Validation

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, Firefox < 87, and Thunderbird < 78.9.

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, Firefox < 87, and Thunderbird < 78.9.

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, Firefox < 87, and Thunderbird < 78.9.

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, Firefox < 87, and Thunderbird < 78.9.

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

Stay on top of Security Vulnerabilities

Want an email whenever new vulnerabilities are published for Mozilla Thunderbird or by Mozilla? Click the Watch button to subscribe.

Mozilla
Vendor

Mozilla Firefox
Open source web browser

subscribe