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CVE-2026-20856— Windows Server Update Service (WSUS) Remote Code Execution Vulnerability

Quick assessment

Affected
Microsoft Windows 10 Version 1607
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Microsoft Windows是美国微软（Microsoft）公司的一套个人设备使用的操作系统。 Microsoft Windows存在输入验证错误漏洞。攻击者利用该漏洞可以远程执行代码。以下产品和版本受到影响：Windows 10 Version 1809 for 32-bit Systems,Windows 10 Version 1809 for x64-based Systems,Windows Server 2019,Windows Server 2019 (Server Core insta

CVSS 8.1 · High EPSS 1.12% · P63

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 20

VendorProduct Version RangeStatus
Microsoft Windows 10 Version 1607 10.0.14393.0< 10.0.14393.8783 affected
Microsoft Windows 10 Version 1809 10.0.17763.0< 10.0.17763.8276 affected
Microsoft Windows 10 Version 21H2 10.0.19044.0< 10.0.19044.6809 affected
Microsoft Windows 10 Version 22H2 10.0.19045.0< 10.0.19045.6809 affected
Microsoft Windows 11 version 23H2 10.0.22631.0< 10.0.22631.6491 affected
Microsoft Windows 11 Version 23H2 10.0.22631.0< 10.0.22631.6491 affected
Microsoft Windows 11 Version 24H2 10.0.26100.0< 10.0.26100.7623 affected
Microsoft Windows 11 Version 25H2 10.0.26200.0< 10.0.26200.7623 affected
Microsoft Windows Server 2012 6.2.9200.0< 6.2.9200.25868 affected
Microsoft Windows Server 2012 (Server Core installation) 6.2.9200.0< 6.2.9200.25868 affected
Microsoft Windows Server 2012 R2 6.3.9600.0< 6.3.9600.22968 affected
Microsoft Windows Server 2012 R2 (Server Core installation) 6.3.9600.0< 6.3.9600.22968 affected
Microsoft Windows Server 2016 10.0.14393.0< 10.0.14393.8783 affected
Microsoft Windows Server 2016 (Server Core installation) 10.0.14393.0< 10.0.14393.8783 affected
Microsoft Windows Server 2019 10.0.17763.0< 10.0.17763.8276 affected
Microsoft Windows Server 2019 (Server Core installation) 10.0.17763.0< 10.0.17763.8276 affected
Microsoft Windows Server 2022 10.0.20348.0< 10.0.20348.4648 affected
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.0< 10.0.25398.2092 affected
Microsoft Windows Server 2025 10.0.26100.0< 10.0.26100.32230 affected
Microsoft Windows Server 2025 (Server Core installation) 10.0.26100.0< 10.0.26100.32230 affected
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I. Basic Information for CVE-2026-20856

Vulnerability Information
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Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
Windows Server Update Service (WSUS) Remote Code Execution Vulnerability
Source: CVE Program / CVE List V5
Vulnerability Description
Improper input validation in Windows Server Update Service allows an unauthorized attacker to execute code over a network.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
输入验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Microsoft Windows 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Microsoft Windows是美国微软（Microsoft）公司的一套个人设备使用的操作系统。 Microsoft Windows存在输入验证错误漏洞。攻击者利用该漏洞可以远程执行代码。以下产品和版本受到影响：Windows 10 Version 1809 for 32-bit Systems,Windows 10 Version 1809 for x64-based Systems,Windows Server 2019,Windows Server 2019 (Server Core insta
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Microsoft Windows 10 Version 1607 10.0.14393.0 ~ 10.0.14393.8783 -
Microsoft Windows 10 Version 1809 10.0.17763.0 ~ 10.0.17763.8276 -
Microsoft Windows 10 Version 21H2 10.0.19044.0 ~ 10.0.19044.6809 -
Microsoft Windows 10 Version 22H2 10.0.19045.0 ~ 10.0.19045.6809 -
Microsoft Windows 11 version 23H2 10.0.22631.0 ~ 10.0.22631.6491 -
Microsoft Windows 11 Version 23H2 10.0.22631.0 ~ 10.0.22631.6491 -
Microsoft Windows 11 Version 24H2 10.0.26100.0 ~ 10.0.26100.7623 -
Microsoft Windows 11 Version 25H2 10.0.26200.0 ~ 10.0.26200.7623 -
Microsoft Windows Server 2012 6.2.9200.0 ~ 6.2.9200.25868 -
Microsoft Windows Server 2012 (Server Core installation) 6.2.9200.0 ~ 6.2.9200.25868 -
Microsoft Windows Server 2012 R2 6.3.9600.0 ~ 6.3.9600.22968 -
Microsoft Windows Server 2012 R2 (Server Core installation) 6.3.9600.0 ~ 6.3.9600.22968 -
Microsoft Windows Server 2016 10.0.14393.0 ~ 10.0.14393.8783 -
Microsoft Windows Server 2016 (Server Core installation) 10.0.14393.0 ~ 10.0.14393.8783 -
Microsoft Windows Server 2019 10.0.17763.0 ~ 10.0.17763.8276 -
Microsoft Windows Server 2019 (Server Core installation) 10.0.17763.0 ~ 10.0.17763.8276 -
Microsoft Windows Server 2022 10.0.20348.0 ~ 10.0.20348.4648 -
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.0 ~ 10.0.25398.2092 -
Microsoft Windows Server 2025 10.0.26100.0 ~ 10.0.26100.32230 -
Microsoft Windows Server 2025 (Server Core installation) 10.0.26100.0 ~ 10.0.26100.32230 -

II. Public POCs for CVE-2026-20856

# POC Description Source Link Shenlong Link
1 None https://github.com/b1gchoi/poc-CVE-2026-20856 POC Details
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No public POC found.

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III. Intelligence Information for CVE-2026-20856

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Same Patch Batch · Microsoft · 2026-01-13 · 112 CVEs total

CVE-2026-20963 9.8 CRITICAL Microsoft SharePoint Remote Code Execution Vulnerability
CVE-2026-20947 8.8 HIGH Microsoft SharePoint Server Remote Code Execution Vulnerability
CVE-2026-20868 8.8 HIGH Windows Routing and Remote Access Service (RRAS) Remote Code Execution Vulnerability
CVE-2026-20952 8.4 HIGH Microsoft Office Remote Code Execution Vulnerability
CVE-2026-20944 8.4 HIGH Microsoft Word Remote Code Execution Vulnerability
CVE-2026-20953 8.4 HIGH Microsoft Office Remote Code Execution Vulnerability
CVE-2026-20931 8.0 HIGH Windows Telephony Service Elevation of Privilege Vulnerability
CVE-2026-20951 7.8 HIGH Microsoft SharePoint Server Remote Code Execution Vulnerability
CVE-2026-20832 7.8 HIGH Windows Remote Procedure Call Interface Definition Language (IDL) Elevation of Privilege V
CVE-2026-20920 7.8 HIGH Win32k Elevation of Privilege Vulnerability
CVE-2026-20843 7.8 HIGH Windows Routing and Remote Access Service (RRAS) Elevation of Privilege Vulnerability
CVE-2026-20938 7.8 HIGH Windows Virtualization-Based Security (VBS) Enclave Elevation of Privilege Vulnerability
CVE-2026-20837 7.8 HIGH Windows Media Remote Code Execution Vulnerability
CVE-2026-21224 7.8 HIGH Azure Connected Machine Agent Elevation of Privilege Vulnerability
CVE-2026-20840 7.8 HIGH Windows NTFS Remote Code Execution Vulnerability
CVE-2026-20956 7.8 HIGH Microsoft Excel Remote Code Execution Vulnerability
CVE-2026-20940 7.8 HIGH Windows Cloud Files Mini Filter Driver Elevation of Privilege Vulnerability
CVE-2026-20865 7.8 HIGH Windows Management Services Elevation of Privilege Vulnerability
CVE-2026-20946 7.8 HIGH Microsoft Excel Remote Code Execution Vulnerability
CVE-2026-20864 7.8 HIGH Windows Connected Devices Platform Service Elevation of Privilege Vulnerability

Showing top 20 of 112 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Windows 10 Version 1607
Same vendor: Microsoft
Same weakness: CWE-20

V. Comments for CVE-2026-20856

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