Unrated severityNVD Advisory· Published Jan 13, 2026· Updated Apr 1, 2026

Windows Server Update Service (WSUS) Remote Code Execution Vulnerability

CVE-2026-20856

Description

Improper input validation in Windows Server Update Service allows an unauthorized attacker to execute code over a network.

Microsoft/Windows Server 2003llm-fuzzy2 versions
(expand)+ 1 more
- (no CPE)
- (no CPE)range: 10.0.20348.0
Microsoft/Windows 10 1607cpe-rescue3 versions
10.0.14393.0+ 2 more
- (no CPE)range: 10.0.14393.0
- (no CPE)range: 10.0.19044.0
- (no CPE)range: 10.0.19045.0
Microsoft/Windows 10 1809cpe-rescue
Range: 10.0.17763.0
Microsoft/Windows 11 version 22H3v5
Range: 10.0.22631.0
Microsoft/Windows 11 23h2cpe-rescue
Range: 10.0.22631.0
Microsoft/Windows 11 24h2cpe-rescue
Range: 10.0.26100.0
Microsoft/Windows 11 25h2cpe-rescue
Range: 10.0.26200.0
Microsoft/Windows Server 2012cpe-rescue2 versions
6.2.9200.0+ 1 more
- (no CPE)range: 6.2.9200.0
- (no CPE)range: 6.3.9600.0
Microsoft/Windows Server 2012 R2 (Server Core installation)v5
Range: 6.3.9600.0
Microsoft/Windows Server 2012 (Server Core installation)v5
Range: 6.2.9200.0
Microsoft/Windows Server 2016cpe-rescue
Range: 10.0.14393.0
Microsoft/Windows Server 2016 (Server Core installation)v5
Range: 10.0.14393.0
Microsoft/Windows Server 2019cpe-rescue
Range: 10.0.17763.0
Microsoft/Windows Server 2019 (Server Core installation)v5
Range: 10.0.17763.0
Microsoft/Windows Server 2022, 23H2 Edition (Server Core installation)v5
Range: 10.0.25398.0
Microsoft/Windows Server 2025cpe-rescue
Range: 10.0.26100.0
Microsoft/Windows Server 2025 (Server Core installation)v5
Range: 10.0.26100.0

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