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CVE-2026-20940 Microsoft CVE debrief

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-01-13T18:16:21.313Z and has not been modified since then. The CVE-2026-20940 vulnerability is a heap-based buffer overflow in the Windows Cloud Files Mini Filter Driver. This vulnerability allows an authorized attacker to elevate privileges locally. The vulnerability affects multiple versions of Windows 10, Windows 11, and Windows Server. Microsoft has provided a patch to fix this vulnerability. System administrators and security teams responsible for managing Windows systems should be aware of this vulnerability and take steps to patch affected systems. Additionally, security teams should monitor system logs for potential exploitation attempts and implement additional security measures to prevent exploitation.

Vendor
Microsoft
Product
Windows 10 Version 1607
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 should be aware of this vulnerability and take steps to patch affected systems. Additionally, security teams should monitor system logs for potential exploitation attempts and implement additional security measures to prevent exploitation.

Technical summary

The CVE-2026-20940 vulnerability is a heap-based buffer overflow in the Windows Cloud Files Mini Filter Driver. This vulnerability allows an authorized attacker to elevate privileges locally. The vulnerability affects multiple versions of Windows 10, Windows 11, and Windows Server. Microsoft has provided a patch to fix this vulnerability.

Defensive priority

This vulnerability allows an authorized attacker to elevate privileges locally, which can have a significant impact on the security of a Windows system. Therefore, it is essential to prioritize patching this vulnerability.

Recommended defensive actions

  • Apply the patch provided by Microsoft to fix the vulnerability.
  • Ensure that all affected systems are updated with the latest security patches.
  • Monitor system logs for potential exploitation attempts.
  • Implement additional security measures, such as access controls and intrusion detection systems.

Evidence notes

The CVE-2026-20940 vulnerability is a heap-based buffer overflow in the Windows Cloud Files Mini Filter Driver. According to the NVD, this vulnerability has a CVSS score of 7.8 and a severity of HIGH. The vulnerability affects multiple versions of Windows 10, Windows 11, and Windows Server.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-20940 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-20940

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

  • CVE-2026-20940 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-20940

    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.