CVE-2026-21241

Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

CVE-2026-21241 is fixed in 13 products on 1 platform, first by KB5075941, released February 10, 2026. It is not reported as exploited, but the vendor rates exploitation more likely. Patch Radar priority: Urgent.

Urgent

CVSS

7.0

Important

Exploitation

More likely

Vendor assessment

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0256

85th percentile

<p>Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.</p>

Where it's fixed

Product	Fixed in	Fix	Released
Microsoft
Windows 11 Version 23H2 for ARM64-based Systems	22631.6649	KB5075941	Feb 10, 2026
Windows 11 Version 23H2 for x64-based Systems	22631.6649	KB5075941	Feb 10, 2026
Windows 11 Version 24H2 for ARM64-based Systems		KB5077212	Feb 10, 2026
Windows 11 Version 24H2 for ARM64-based Systems		KB5077181	Feb 10, 2026
Windows 11 Version 24H2 for x64-based Systems		KB5077212	Feb 10, 2026
Windows 11 Version 24H2 for x64-based Systems		KB5077181	Feb 10, 2026
Windows 11 Version 25H2 for ARM64-based Systems		KB5077212	Feb 10, 2026
Windows 11 Version 25H2 for ARM64-based Systems		KB5077181	Feb 10, 2026
Windows 11 Version 25H2 for x64-based Systems		KB5077212	Feb 10, 2026
Windows 11 Version 25H2 for x64-based Systems		KB5077181	Feb 10, 2026
Windows 11 Version 26H1 for ARM64-based Systems	28000.1575	KB5077179	Feb 10, 2026
Windows 11 version 26H1 for x64-based Systems	28000.1575	KB5077179	Feb 10, 2026
Windows Server 2022	20348.4773	KB5075906	Feb 10, 2026
Windows Server 2022	20348.4711	KB5075943	Feb 10, 2026
Windows Server 2022 (Server Core installation)	20348.4773	KB5075906	Feb 10, 2026
Windows Server 2022 (Server Core installation)	20348.4711	KB5075943	Feb 10, 2026
Windows Server 2022, 23H2 Edition (Server Core installation)	25398.2149	KB5075897	Feb 10, 2026
Windows Server 2025	26100.32313	KB5075942	Feb 10, 2026
Windows Server 2025	26100.32370	KB5075899	Feb 10, 2026
Windows Server 2025 (Server Core installation)	26100.32313	KB5075942	Feb 10, 2026
Windows Server 2025 (Server Core installation)	26100.32370	KB5075899	Feb 10, 2026

Details

Published
February 10, 2026
Weakness
Use After Free
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21241

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