Windows Local Session Manager (LSM) Elevation of Privilege Vulnerability
This high-severity Microsoft Server advisory covers CVE-2026-20869 affecting Windows Server 2008 R2 Service Pack 1 (Server Core installation), Windows Server 2008 Service Pack 2 (Server Core installation), Windows Server 2012 (Server Core installation).
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Summary
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Local Session Manager (LSM) allows an authorized attacker to elevate privileges locally.
Affected products named by the advisory: Windows Server 2008 R2 Service Pack 1; Windows Server 2008 R2 Service Pack 1 (Server Core installation); Windows Server 2008 Service Pack 2; Windows Server 2008 Service Pack 2 (Server Core installation); and 12 more.
Affected products named by the advisory: Windows Server 2012 (Server Core installation); Windows Server 2012 R2 (Server Core installation); Windows Server 2016 (Server Core installation); Windows Server 2019 (Server Core installation); and 2 more.
- Windows 10 Version 1607 10.0.14393.0 before 10.0.14393.8783
- Windows 10 Version 1809 10.0.17763.0 before 10.0.17763.8276
- Windows 10 Version 21H2 10.0.19044.0 before 10.0.19044.6809
- Windows 10 Version 22H2 10.0.19045.0 before 10.0.19045.6809
- Windows 11 version 23H2 10.0.22631.0 before 10.0.22631.6491
- Windows 11 Version 23H2 10.0.22631.0 before 10.0.22631.6491
- Windows 11 Version 24H2 10.0.26100.0 before 10.0.26100.7623
- Windows 11 Version 25H2 10.0.26200.0 before 10.0.26200.7623
- Windows Server 2008 R2 Service Pack 1 6.1.7601.0 before 6.1.7601.28117
- Windows Server 2008 R2 Service Pack 1 (Server Core installation) 6.1.7601.0 before 6.1.7601.28117
- Windows Server 2008 Service Pack 2 6.0.6003.0 before 6.0.6003.23717
- Windows Server 2008 Service Pack 2 (Server Core installation) 6.0.6003.0 before 6.0.6003.23717
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
- 10.0.14393.8783
- 10.0.17763.8276
- 10.0.19044.6809
- 10.0.19045.6809
- 10.0.22631.6491
- 10.0.26100.7623
- 10.0.26200.7623
- 6.1.7601.28117
- 6.0.6003.23717
- 6.2.9200.25868
- 6.3.9600.22968
- 10.0.20348.4648
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
Mitigation
Upgrade to a fixed release: 10.0.14393.8783, 10.0.17763.8276, 10.0.19044.6809, 10.0.19045.6809, 10.0.22631.6491, 10.0.26100.7623. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
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