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CVE-2026-20871 Microsoft CVE debrief

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-01-13T18:16:16.810Z and has not been modified since then. The CVE-2026-20871 vulnerability is a use-after-free issue in the Desktop Windows Manager that allows an authorized attacker to elevate privileges locally. The vulnerability has a CVSS score of 7.8 and affects various versions of Windows 10, Windows 11, and Windows Server. Microsoft has provided patches and mitigations to address this vulnerability. Administrators and users of Windows 10, Windows 11, and Windows Server systems should be aware of this vulnerability and take necessary actions to apply patches or mitigations to prevent exploitation. It is essential to apply the necessary patches or mitigations to prevent exploitation, and to monitor systems for suspicious activity that may indicate exploitation of this vulnerability.

Vendor
Microsoft
Product
Windows 10 Version 21H2
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-01-13
Original CVE updated
2026-07-30
Advisory published
2026-01-13
Advisory updated
2026-07-30

Who should care

Administrators and users of Windows 10, Windows 11, and Windows Server systems should be aware of this vulnerability and take necessary actions to apply patches or mitigations to prevent exploitation.

Technical summary

The CVE-2026-20871 vulnerability is a use-after-free issue in the Desktop Windows Manager that allows an authorized attacker to elevate privileges locally. The vulnerability has a CVSS score of 7.8 and affects various versions of Windows 10, Windows 11, and Windows Server. Microsoft has provided patches and mitigations to address this vulnerability.

Defensive priority

This vulnerability allows an authorized attacker to elevate privileges locally, which can have a significant impact on the security of the system. Therefore, it is essential to apply the necessary patches or mitigations to prevent exploitation.

Recommended defensive actions

  • Apply patches or mitigations provided by Microsoft to address the vulnerability.
  • Ensure that all affected systems are updated with the latest security patches.
  • Monitor systems for suspicious activity that may indicate exploitation of this vulnerability.

Evidence notes

The CVE-2026-20871 record indicates a use-after-free vulnerability in the Desktop Windows Manager, which can be exploited locally to elevate privileges. The vulnerability has a CVSS score of 7.8 and is classified as HIGH severity. Affected products include various versions of Windows 10, Windows 11, and Windows Server.

Official resources

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-01-13T18:16:16.810Z and has not been modified since then.