Microsoft Windows up to Server 2022 MSHTML path traversal

Summaryinfo

A vulnerability labeled as very critical has been found in Microsoft Windows. The affected element is an unknown function of the component MSHTML. Executing a manipulation can lead to an unknown weakness. This vulnerability is tracked as CVE-2021-40444. The attack can be launched remotely. Moreover, an exploit is present. Modifying the configuration settings is advised.

Detailsinfo

A vulnerability was found in Microsoft Windows (Operating System). It has been declared as very critical. This vulnerability affects an unknown part of the component MSHTML. The CWE definition for the vulnerability is CWE-22. The product 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 product 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. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

<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>

The weakness was disclosed 09/07/2021 as confirmed security guidance (Website). The advisory is available at portal.msrc.microsoft.com. This vulnerability was named CVE-2021-40444. Successful exploitation requires user interaction by the victim. Technical details are unknown but an exploit is available. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 12/16/2025). This vulnerability is assigned to T1006 by the MITRE ATT&CK project.

It is declared as attacked. This issue was added on 11/03/2021 to the CISA Known Exploited Vulnerabilities Catalog with a due date of 11/17/2021:

Apply updates per vendor instructions.

It is possible to mitigate the problem by applying the configuration setting . A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Zero-Day.cz (660) and EUVD (EUVD-2021-27621). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

• Operating System

Vendor

• Microsoft

Name

• Windows

Version

• 7 SP1
• 8.1
• 10
• 10 20H2
• 10 21H1
• 10 1607
• 10 1809
• 10 1909
• 10 2004
• RT 8.1
• Server 20H2
• Server 2004
• Server 2008 R2 SP1
• Server 2008 SP2
• Server 2012
• Server 2012 R2
• Server 2016
• Server 2019
• Server 2022

License

• commercial

Website

• Vendor: https://www.microsoft.com/
• Product: https://www.microsoft.com/en-us/windows

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Entryinfo

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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