Sep 2021: Microsoft MSHTML Remote Code Execution Vulnerability
CVE-2021-40444 Published on September 15, 2021
Microsoft MSHTML Remote Code Execution Vulnerability
<p>Microsoft is investigating reports of a remote code execution vulnerability in MSHTML that affects Microsoft Windows. Microsoft is aware of targeted attacks that attempt to exploit this vulnerability by using specially-crafted Microsoft Office documents.</p>
<p>An attacker could craft a malicious ActiveX control to be used by a Microsoft Office document that hosts the browser rendering engine. The attacker would then have to convince the user to open the malicious document. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.</p>
<p>Microsoft Defender Antivirus and Microsoft Defender for Endpoint both provide detection and protections for the known vulnerability. Customers should keep antimalware products up to date. Customers who utilize automatic updates do not need to take additional action. Enterprise customers who manage updates should select the detection build 1.349.22.0 or newer and deploy it across their environments. Microsoft Defender for Endpoint alerts will be displayed as: Suspicious Cpl File Execution.</p>
<p>Upon completion of this investigation, Microsoft will take the appropriate action to help protect our customers. This may include providing a security update through our monthly release process or providing an out-of-cycle security update, depending on customer needs.</p>
<p>Please see the <strong>Mitigations</strong> and <strong>Workaround</strong> sections for important information about steps you can take to protect your system from this vulnerability.</p>
<p><strong>UPDATE</strong> September 14, 2021: Microsoft has released security updates to address this vulnerability. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. Please see the FAQ for important information about which updates are applicable to your system.</p>
Known Exploited Vulnerability
This Microsoft Windows, Server (spec. IE) All Arbitrary Code Execution vulnerability is part of CISA's list of Known Exploited Vulnerabilities. Microsoft MSHTML Remote Code Execution Vulnerability.
The following remediation steps are recommended / required by November 17, 2021: Apply updates per vendor instructions.
Weakness Type
What is a Directory traversal Vulnerability?
The software uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the software does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
CVE-2021-40444 has been classified to as a Directory traversal vulnerability or weakness.
Products Associated with CVE-2021-40444
You can be notified by email with stack.watch whenever vulnerabilities like CVE-2021-40444 are published in these products:
Affected Versions
Microsoft Windows 10 Version 1809:- Version 10.0.0 and below 10.0.17763.2183 is affected.
- Version 10.0.0 and below 10.0.17763.2183 is affected.
- Version 10.0.0 and below 10.0.17763.2183 is affected.
- Version 10.0.0 and below 10.0.18363.1801 is affected.
- Version 10.0.0 and below 10.0.19043.1237 is affected.
- Version 10.0.0 and below 10.0.20348.230 is affected.
- Version 10.0.0 and below 10.0.19041.1237 is affected.
- Version 10.0.0 and below 10.0.19041.1237 is affected.
- Version 10.0.0 and below 10.0.19042.1237 is affected.
- Version 10.0.0 and below 10.0.19042.1237 is affected.
- Version 10.0.0 and below 10.0.10240.19060 is affected.
- Version 10.0.0 and below 10.0.14393.4651 is affected.
- Version 10.0.0 and below 10.0.14393.4651 is affected.
- Version 10.0.0 and below 10.0.14393.4651 is affected.
- Version 6.1.0 and below 6.1.7601.25712 is affected.
- Version 6.1.0 and below 1.001 is affected.
- Version 6.1.0 and below 6.1.7601.26221 is affected.
- Version 6.1.0 and below 6.1.7601.25712 is affected.
- Version 6.1.0 and below 1.001 is affected.
- Version 6.1.0 and below 6.1.7601.26221 is affected.
- Version 6.3.0 and below 6.3.9600.20120 is affected.
- Version 6.3.0 and below 1.001 is affected.
- Version 6.0.0 and below 6.0.6003.21218 is affected.
- Version 6.0.0 and below 1.001 is affected.
- Version 6.0.0 and below 6.0.6003.21218 is affected.
- Version 6.0.0 and below 1.001 is affected.
- Version 6.0.0 and below 6.0.6003.21218 is affected.
- Version 6.0.0 and below 1.001 is affected.
- Version 6.1.0 and below 6.1.7601.25712 is affected.
- Version 6.1.0 and below 1.001 is affected.
- Version 6.0.0 and below 6.1.7601.25712 is affected.
- Version 6.0.0 and below 1.001 is affected.
- Version 6.2.0 and below 6.2.9200.23462 is affected.
- Version 6.2.0 and below 1.001 is affected.
- Version 6.2.0 and below 6.2.9200.23462 is affected.
- Version 6.2.0 and below 1.001 is affected.
- Version 6.3.0 and below 6.3.9600.20120 is affected.
- Version 6.3.0 and below 1.001 is affected.
- Version 6.3.0 and below 6.3.9600.20120 is affected.
- Version 6.3.0 and below 1.001 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.