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CVE-2026-20811 Microsoft CVE debrief

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-01-13T18:16:07.727Z and has not been modified since then. The CVE-2026-20811 vulnerability is caused by an access of resource using incompatible type ('type confusion') in Windows Win32K - ICOMP. This vulnerability allows an authorized attacker to elevate privileges locally. The CVSS score is 7.8, indicating a high severity vulnerability. The vulnerability affects multiple versions of Windows, including Windows 11 23H2, Windows 11 24H2, Windows 11 25H2, Windows Server 2022, Windows Server 2022 23H2, and Windows Server 2025. System administrators and security teams should be aware of this vulnerability and take necessary actions to mitigate it.

Vendor
Microsoft
Product
Windows 11 version 23H2
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

System administrators and security teams responsible for managing Windows systems, particularly those using Windows 11 23H2, Windows 11 24H2, Windows 11 25H2, Windows Server 2022, Windows Server 2022 23H2, and Windows Server 2025, should be aware of this vulnerability and take necessary actions to mitigate it.

Technical summary

The CVE-2026-20811 vulnerability is caused by an access of resource using incompatible type ('type confusion') in Windows Win32K - ICOMP. This vulnerability allows an authorized attacker to elevate privileges locally. The CVSS score is 7.8, indicating a high severity vulnerability. The vulnerability affects multiple versions of Windows, including Windows 11 23H2, Windows 11 24H2, Windows 11 25H2, Windows Server 2022, Windows Server 2022 23H2, and Windows Server 2025.

Defensive priority

This vulnerability allows an authorized attacker to elevate privileges locally, which can have a significant impact on the security of a 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 system logs for potential exploitation attempts.
  • Implement additional security controls, such as access controls and intrusion detection systems, to detect and prevent exploitation.

Evidence notes

The CVE-2026-20811 vulnerability is caused by an access of resource using incompatible type ('type confusion') in Windows Win32K - ICOMP. The CVSS score is 7.8, indicating a high severity vulnerability. The vulnerability affects multiple versions of Windows, including Windows 11 23H2, Windows 11 24H2, Windows 11 25H2, Windows Server 2022, Windows Server 2022 23H2, and Windows Server 2025.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-20811 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-20811

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-20811 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-20811

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.