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CVE-2026-20821 Microsoft CVE debrief

The CVE-2026-20821 vulnerability is related to the exposure of sensitive information to an unauthorized actor in Windows Remote Procedure Call. This allows an unauthorized attacker to disclose information locally. The vulnerability has a CVSS score of 6.2 and a vector of CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Various versions of Windows 10, Windows 11, and Windows Server are affected. Organizations should review their deployments and prioritize patching to prevent potential local information disclosure.

Vendor
Microsoft
Product
Windows 10 Version 1607
CVSS
MEDIUM 6.2
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

Organizations using affected versions of Windows 10, Windows 11, and Windows Server should prioritize patching this vulnerability to prevent potential local information disclosure. Affected operators and security teams should review their deployments and assess the potential impact on their environment.

Technical summary

The CVE-2026-20821 vulnerability is related to the exposure of sensitive information to an unauthorized actor in Windows Remote Procedure Call. This allows an unauthorized attacker to disclose information locally. The vulnerability has a CVSS score of 6.2 and a vector of CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Various versions of Windows 10, Windows 11, and Windows Server are affected.

Defensive priority

Medium priority given the CVSS score of 6.2 and the potential for local information disclosure.

Recommended defensive actions

  • Apply vendor patches
  • Review and update vulnerability management processes
  • Monitor system logs for suspicious activity
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE-2026-20821 record indicates an exposure of sensitive information to an unauthorized actor in Windows Remote Procedure Call. According to the NVD, this vulnerability allows an unauthorized attacker to disclose information locally. The CVSS score is 6.2, with a vector of CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Affected products include various versions of Windows 10, Windows 11, and Windows Server.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-20821 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-20821

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

  • CVE-2026-20821 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-20821

    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.