Feb 2026: Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
CVE-2026-21238 Published on February 10, 2026

Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
Improper access control in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

Vendor Advisory NVD

Weakness Type

What is an Authorization Vulnerability?

The software does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

CVE-2026-21238 has been classified to as an Authorization vulnerability or weakness.

Products Associated with CVE-2026-21238

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Microsoft Windows 11 26h1

Microsoft Windows 10

Microsoft Windows Server 2019

Microsoft Windows Server 2022

Microsoft Windows Server 2025

Microsoft Windows 11 25h2

Microsoft Windows 11 23h2

Microsoft Windows Server 23h2

Microsoft Windows 11 24h2

Microsoft Windows Server 2016

Microsoft Windows Server 2012

Microsoft Windows Server 2012 R2

Affected Versions

Microsoft Windows 10 Version 1607:

Version 10.0.14393.0 and below 10.0.14393.8868 is affected.

Microsoft Windows 10 Version 1809:

Version 10.0.17763.0 and below 10.0.17763.8389 is affected.

Microsoft Windows 10 Version 21H2:

Version 10.0.19044.0 and below 10.0.19044.6937 is affected.

Microsoft Windows 10 Version 22H2:

Version 10.0.19045.0 and below 10.0.19045.6937 is affected.

Microsoft Windows 11 version 22H3:

Version 10.0.22631.0 and below 10.0.22631.6649 is affected.

Microsoft Windows 11 Version 23H2:

Version 10.0.22631.0 and below 10.0.22631.6649 is affected.

Microsoft Windows 11 Version 24H2:

Version 10.0.26100.0 and below 10.0.26100.7840 is affected.

Microsoft Windows 11 Version 25H2:

Version 10.0.26200.0 and below 10.0.26200.7840 is affected.

Microsoft Windows 11 version 26H1:

Version 10.0.28000.0 and below 10.0.28000.1575 is affected.

Microsoft Windows 11 Version 26H1:

Version 10.0.28000.0 and below 10.0.28000.1575 is affected.

Microsoft Windows Server 2012:

Version 6.2.9200.0 and below 6.2.9200.25923 is affected.

Microsoft Windows Server 2012 (Server Core installation):

Version 6.2.9200.0 and below 6.2.9200.25923 is affected.

Microsoft Windows Server 2012 R2:

Version 6.3.9600.0 and below 6.3.9600.23022 is affected.

Microsoft Windows Server 2012 R2 (Server Core installation):

Version 6.3.9600.0 and below 6.3.9600.23022 is affected.

Microsoft Windows Server 2016:

Version 10.0.14393.0 and below 10.0.14393.8868 is affected.

Microsoft Windows Server 2016 (Server Core installation):

Version 10.0.14393.0 and below 10.0.14393.8868 is affected.

Microsoft Windows Server 2019:

Version 10.0.17763.0 and below 10.0.17763.8389 is affected.

Microsoft Windows Server 2019 (Server Core installation):

Version 10.0.17763.0 and below 10.0.17763.8389 is affected.

Microsoft Windows Server 2022:

Version 10.0.20348.0 and below 10.0.20348.4773 is affected.

Microsoft Windows Server 2022, 23H2 Edition (Server Core installation):

Version 10.0.25398.0 and below 10.0.25398.2149 is affected.

Microsoft Windows Server 2025:

Version 10.0.26100.0 and below 10.0.26100.32370 is affected.

Microsoft Windows Server 2025 (Server Core installation):

Version 10.0.26100.0 and below 10.0.26100.32370 is affected.

Exploit Probability

EPSS

0.02%

Percentile

5.86%