Microsoft Windows up to Server 2019 Application Compatibility Client Library access control

Summaryinfo

A vulnerability was found in Microsoft Windows. It has been rated as critical. Affected by this issue is some unknown functionality of the component Application Compatibility Client Library. Performing a manipulation results in access control. This vulnerability was named CVE-2020-16920. The attack may be initiated remotely. There is no available exploit. To fix this issue, it is recommended to deploy a patch.

Detailsinfo

A vulnerability classified as critical has been found in Microsoft Windows (Operating System). This affects an unknown function of the component Application Compatibility Client Library. The manipulation with an unknown input leads to a access control vulnerability. CWE is classifying the issue as CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

<p>An elevation of privilege vulnerability exists when the Windows Application Compatibility Client Library improperly handles registry operations. An attacker who successfully exploited this vulnerability could gain elevated privileges.</p> <p>To exploit the vulnerability, an attacker would first need code execution on a victim system. An attacker could then run a specially crafted application.</p> <p>The security update addresses the vulnerability by ensuring the Windows Application Compatibility Client Library properly handles registry operations.</p>

The weakness was presented 10/13/2020 as confirmed security guidance (Website). It is possible to read the advisory at portal.msrc.microsoft.com. This vulnerability is uniquely identified as CVE-2020-16920. The exploitability is told to be easy. It is possible to initiate the attack remotely. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 02/24/2026). The attack technique deployed by this issue is T1068 according to MITRE ATT&CK. The advisory points out:

An elevation of privilege vulnerability exists when the Windows Application Compatibility Client Library improperly handles registry operations. An attacker who successfully exploited this vulnerability could gain elevated privileges. To exploit the vulnerability, an attacker would first need code execution on a victim system. An attacker could then run a specially crafted application. The security update addresses the vulnerability by ensuring the Windows Application Compatibility Client Library properly handles registry operations.

It is declared as proof-of-concept.

Applying a patch is able to eliminate this problem. A possible mitigation has been published immediately after the disclosure of the vulnerability.

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Microsoft

Name

• Windows

Version

• 7 SP1
• 8.1
• 10
• 10 1607
• 10 1709
• 10 1803
• 10 1809
• 10 1903
• 10 1909
• 10 2004
• RT 8.1
• Server 1903
• Server 1909
• Server 2004
• Server 2008 R2 SP1
• Server 2008 SP2
• Server 2012
• Server 2012 R2
• Server 2016
• Server 2019

License

• commercial

Website

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

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