CVE-2026-20859

Windows Kernel-Mode Driver Elevation of Privilege Vulnerability

CVE-2026-20859 is fixed in 6 products on 1 platform, first by KB5074109, 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

0.0048

41st percentile

<p>Use after free in Windows Kernel-Mode Drivers allows an authorized attacker to elevate privileges locally.</p>

Where it's fixed

Product	Fixed in	Fix	Released
Microsoft
Windows 11 Version 24H2 for ARM64-based Systems		KB5074109	Jan 13, 2026
Windows 11 Version 24H2 for x64-based Systems		KB5074109	Jan 13, 2026
Windows 11 Version 25H2 for ARM64-based Systems		KB5074109	Jan 13, 2026
Windows 11 Version 25H2 for x64-based Systems		KB5074109	Jan 13, 2026
Windows Server 2025	26100.32230	KB5073379	Jan 13, 2026
Windows Server 2025 (Server Core installation)	26100.32230	KB5073379	Jan 13, 2026

Details

Published
January 13, 2026
Weakness
Use After Free
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20859

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