CVE-2026-20810

Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

CVE-2026-20810 is fixed in 10 products on 1 platform, first by KB5073723, released January 13, 2026. It is not reported as exploited. Patch Radar priority: High.

High

CVSS

7.8

Important

Exploitation

None reported

Exploitation Less Likely

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0049

42nd percentile

<p>Free of memory not on the heap 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 10 Version 1809 for 32-bit Systems	17763.8276	KB5073723	Jan 13, 2026
Windows 10 Version 1809 for x64-based Systems	17763.8276	KB5073723	Jan 13, 2026
Windows 10 Version 21H2 for 32-bit Systems		KB5073724	Jan 13, 2026
Windows 10 Version 21H2 for ARM64-based Systems		KB5073724	Jan 13, 2026
Windows 10 Version 21H2 for x64-based Systems		KB5073724	Jan 13, 2026
Windows 10 Version 22H2 for 32-bit Systems		KB5073724	Jan 13, 2026
Windows 10 Version 22H2 for ARM64-based Systems		KB5073724	Jan 13, 2026
Windows 10 Version 22H2 for x64-based Systems		KB5073724	Jan 13, 2026
Windows Server 2019	17763.8276	KB5073723	Jan 13, 2026
Windows Server 2019 (Server Core installation)	17763.8276	KB5073723	Jan 13, 2026

Details

Published
January 13, 2026
Weakness
Free of Memory not on the Heap
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20810

For tools and AI agents

This page as data: JSON · Markdown

Link to this page

If this page saved you time, a link to it in your ticket, advisory or write-up helps others find it.

HTML

<a href="https://patchblox.com/security/cve/CVE-2026-20810">CVE-2026-20810 on Patchblox Patch Radar</a>

Reusing the data? How to credit Patch Radar.

Is this on your machines?

Patchblox finds every install below the fixed version on Windows, macOS and Linux, and updates them through your release rings.

Get a demo

Patch Radar data is free to use with attribution. Terms and how to credit it.

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.