HarborGuard / CVE
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HIGHCVE-2026-20856Published Modified CNA microsoft

CVE-2026-20856: 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.

Metrics

CVSS v3.1
8.1
Severity
HIGH
Fixed in
6.2.9200.25868
Affected Products
20

Fix available

6.2.9200.258686.3.9600.2296810.0.14393.878310.0.17763.827610.0.19044.680910.0.19045.680910.0.20348.464810.0.22631.649110.0.25398.209210.0.26100.762310.0.26100.3223010.0.26200.7623
Patch commits
Affected packages
  • Microsoft / Windows 10 Version 1607
    < 10.0.14393.8783 (from 10.0.14393.0)
  • Microsoft / Windows 10 Version 1809
    < 10.0.17763.8276 (from 10.0.17763.0)
  • Microsoft / Windows 10 Version 21H2
    < 10.0.19044.6809 (from 10.0.19044.0)
  • Microsoft / Windows 10 Version 22H2
    < 10.0.19045.6809 (from 10.0.19045.0)
  • Microsoft / Windows 11 version 22H3
    < 10.0.22631.6491 (from 10.0.22631.0)
  • Microsoft / Windows 11 Version 23H2
    < 10.0.22631.6491 (from 10.0.22631.0)
  • Microsoft / Windows 11 Version 24H2
    < 10.0.26100.7623 (from 10.0.26100.0)
  • Microsoft / Windows 11 Version 25H2
    < 10.0.26200.7623 (from 10.0.26200.0)
  • Microsoft / Windows Server 2012
    < 6.2.9200.25868 (from 6.2.9200.0)
  • Microsoft / Windows Server 2012 (Server Core installation)
    < 6.2.9200.25868 (from 6.2.9200.0)
  • Microsoft / Windows Server 2012 R2
    < 6.3.9600.22968 (from 6.3.9600.0)
  • Microsoft / Windows Server 2012 R2 (Server Core installation)
    < 6.3.9600.22968 (from 6.3.9600.0)
  • Microsoft / Windows Server 2016
    < 10.0.14393.8783 (from 10.0.14393.0)
  • Microsoft / Windows Server 2016 (Server Core installation)
    < 10.0.14393.8783 (from 10.0.14393.0)
  • Microsoft / Windows Server 2019
    < 10.0.17763.8276 (from 10.0.17763.0)
  • Microsoft / Windows Server 2019 (Server Core installation)
    < 10.0.17763.8276 (from 10.0.17763.0)
  • Microsoft / Windows Server 2022
    < 10.0.20348.4648 (from 10.0.20348.0)
  • Microsoft / Windows Server 2022, 23H2 Edition (Server Core installation)
    < 10.0.25398.2092 (from 10.0.25398.0)
  • Microsoft / Windows Server 2025
    < 10.0.26100.32230 (from 10.0.26100.0)
  • Microsoft / Windows Server 2025 (Server Core installation)
    < 10.0.26100.32230 (from 10.0.26100.0)
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
References