CVE-2026-20856: CWE-20: Improper Input Validation in Microsoft Windows 10 Version 1607
Improper input validation in Windows Server Update Service allows an unauthorized attacker to execute code over a network.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-20856) involves improper input validation in the Windows Server Update Service component of Microsoft Windows 10 Version 1607 (build 10.0.14393.0). The flaw enables an unauthenticated attacker to execute arbitrary code remotely, potentially leading to full system compromise. The CVSS v3.1 base score is 8.1, indicating high severity, with network attack vector, high attack complexity, no privileges or user interaction required, and high impact on confidentiality, integrity, and availability. Microsoft has published an official fix to remediate this vulnerability.
Potential Impact
Successful exploitation allows remote code execution without authentication, which can lead to complete compromise of the affected system's confidentiality, integrity, and availability.
Mitigation Recommendations
An official fix is available from Microsoft. Users and administrators should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20856 to remediate this vulnerability.
CVE-2026-20856: CWE-20: Improper Input Validation in Microsoft Windows 10 Version 1607
Description
Improper input validation in Windows Server Update Service allows an unauthorized attacker to execute code over a network.
CVSS v3.1
Score 8.1high
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-20856) involves improper input validation in the Windows Server Update Service component of Microsoft Windows 10 Version 1607 (build 10.0.14393.0). The flaw enables an unauthenticated attacker to execute arbitrary code remotely, potentially leading to full system compromise. The CVSS v3.1 base score is 8.1, indicating high severity, with network attack vector, high attack complexity, no privileges or user interaction required, and high impact on confidentiality, integrity, and availability. Microsoft has published an official fix to remediate this vulnerability.
Potential Impact
Successful exploitation allows remote code execution without authentication, which can lead to complete compromise of the affected system's confidentiality, integrity, and availability.
Mitigation Recommendations
An official fix is available from Microsoft. Users and administrators should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20856 to remediate this vulnerability.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- microsoft
- Date Reserved
- 2025-12-03T05:54:20.380Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- official-fix
- Vendor Advisory Urls
- [{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20856","vendor":"Microsoft"}]
Threat ID: 69668ae0a60475309f9ae102
Added to database: 01/13/2026, 18:11:44 UTC
Last enriched: 07/30/2026, 23:44:45 UTC
Last updated: 09/10/2026, 19:36:52 UTC
Views: 217
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