CVE-2026-20869: Microsoft Windows race condition in Local Session Manager

CVE-2026-20869 · Severity: high · CVSS 7 · Published 2026-01-13

A security vulnerability exists in the Windows Local Session Manager, a component responsible for managing user sessions on a computer. An attacker who already has basic access to a system could exploit a timing error to gain full administrative control. This could allow them to access sensitive data, install malicious software, or disrupt business operations.

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

Quick answers

Is CVE-2026-20869 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-20869 being exploited in the wild.
How severe is CVE-2026-20869?
High severity, with a CVSS score of 7, 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-2026-20869?
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-2026-20869 attacked?
It is attacked with local access, in an operating system.
Am I affected by CVE-2026-20869?
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

A race condition vulnerability (CWE-362) exists in the Windows Local Session Manager (LSM) due to improper synchronization when accessing shared resources. To exploit this, an attacker must first have local access to the target system with low-level user privileges. By successfully winning the race condition during concurrent execution, the attacker can elevate their privileges to SYSTEM or Administrator level. The attack complexity is considered high because it requires specific timing to exploit the shared resource conflict. Microsoft has released security updates to address this issue across affected Windows and Windows Server versions.

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

References

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