CVE-2026-20810

Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

State: Published
Severity: 7.8 High
Published: Jan 13, 2026
Updated: Jul 30, 2026
Reserved: Dec 3, 2025

Description

Free of memory not on the heap in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C	microsoft

Weaknesses

CWE-590 Free of Memory not on the Heap

Affected Products

Product	Versions
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 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

References

Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerabilityvendor-advisorypatch

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