CVE-2026-20934

Windows SMB Server Elevation of Privilege Vulnerability

State: Published
Severity: 7.5 High
Published: Jan 13, 2026
Updated: Jul 30, 2026
Reserved: Dec 4, 2025

Description

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to elevate privileges over a network.

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C	microsoft

Weaknesses

CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Affected Products

Product	Versions
Windows 10 Version 1607Microsoft	10.0.14393.0 to before 10.0.14393.8783Affected
Windows 10 Version 1809Microsoft	10.0.17763.0 to before 10.0.17763.8276Affected
Windows 10 Version 21H2Microsoft	10.0.19044.0 to before 10.0.19044.6809Affected
Windows 10 Version 22H2Microsoft	10.0.19045.0 to before 10.0.19045.6809Affected
Windows 11 version 23H2Microsoft	10.0.22631.0 to before 10.0.22631.6491Affected
Windows 11 Version 23H2Microsoft	10.0.22631.0 to before 10.0.22631.6491Affected
Windows 11 Version 24H2Microsoft	10.0.26100.0 to before 10.0.26100.7623Affected
Windows 11 Version 25H2Microsoft	10.0.26200.0 to before 10.0.26200.7623Affected
Windows Server 2012Microsoft	6.2.9200.0 to before 6.2.9200.25868Affected
Windows Server 2012 (Server Core installation)Microsoft	6.2.9200.0 to before 6.2.9200.25868Affected
Windows Server 2012 R2Microsoft	6.3.9600.0 to before 6.3.9600.22968Affected
Windows Server 2012 R2 (Server Core installation)Microsoft	6.3.9600.0 to before 6.3.9600.22968Affected
Windows Server 2016Microsoft	10.0.14393.0 to before 10.0.14393.8783Affected
Windows Server 2016 (Server Core installation)Microsoft	10.0.14393.0 to before 10.0.14393.8783Affected
Windows Server 2019Microsoft	10.0.17763.0 to before 10.0.17763.8276Affected
Windows Server 2019 (Server Core installation)Microsoft	10.0.17763.0 to before 10.0.17763.8276Affected
Windows Server 2022Microsoft	10.0.20348.0 to before 10.0.20348.4648Affected
Windows Server 2022, 23H2 Edition (Server Core installation)Microsoft	10.0.25398.0 to before 10.0.25398.2092Affected
Windows Server 2025Microsoft	10.0.26100.0 to before 10.0.26100.32230Affected
Windows Server 2025 (Server Core installation)Microsoft	10.0.26100.0 to before 10.0.26100.32230Affected

References

Windows SMB Server Elevation of Privilege Vulnerabilityvendor-advisorypatch

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