CVE-2026-20856

Microsoft · Published January 13, 2026

8.1

CVSS v3.1

HIGH

Patch availableGet patch

Description

Windows Server Update Service (WSUS) Remote Code Execution Vulnerability. Improper input validation in Windows Server Update Service allows an unauthorized attacker to execute code over a network.

Affected Products

Windows 10 Version 1809 for 32-bit Systems
Windows 10 Version 1809 for x64-based Systems
Windows Server 2019
Windows Server 2019 (Server Core installation)

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C