CVE-2026-20821: Microsoft Windows RPC information disclosure

CVE-2026-20821 · Severity: medium · CVSS 6.2 · Published 2026-01-13

A security vulnerability has been identified in the Windows Remote Procedure Call (RPC) mechanism, a core component that allows different programs to communicate with each other. An attacker with local access to a system could exploit this flaw to view sensitive information that should otherwise be protected. While this does not allow for remote control of the computer, it could lead to the exposure of confidential data or help an attacker plan further actions.

Technologies: Microsoft Windows 11, Microsoft Windows Server 2008 R2, Microsoft Windows 10. Vendors: Microsoft.

Quick answers

Is CVE-2026-20821 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-20821 being exploited in the wild.
How severe is CVE-2026-20821?
Medium severity, with a CVSS score of 6.2, published 13 January 2026.
Which products and versions are affected?
Microsoft Windows 11 22H3, 23H2, 24H2, 25H2; Microsoft Windows Server 2008 R2 Service Pack 1; Microsoft Windows 10 1607, 1809, 21H2, 22H2.
Is there a fix for CVE-2026-20821?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-20821 attacked?
It is attacked with local access, in an operating system.
Am I affected by CVE-2026-20821?
Check whether you run Microsoft Windows 11, Microsoft Windows Server 2008 R2 or Microsoft Windows 10 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

An information disclosure vulnerability exists in the Windows Remote Procedure Call (RPC) runtime. The flaw is classified under CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor). An attacker must have local access to the target system to exploit this vulnerability; however, no special privileges or user interaction are required. Successful exploitation allows the attacker to read sensitive memory or system information, potentially facilitating further compromise. Microsoft has released security updates to address this issue across various versions of Windows and Windows Server.

Affected products

  • Microsoft Windows 10 1607, 1809, 21H2, 22H2
  • Microsoft Windows 11 22H3, 23H2, 24H2, 25H2
  • Microsoft Windows Server 2008 R2 Service Pack 1

Timeline

  • 2026-01-13: advisory: Initial disclosure by Microsoft and NVD
  • 2026-07-30: other: CPE and affected version records updated by Microsoft

References

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