MSRC-CVE-2026-26154 — Windows Server Update Service (WSUS) Tampering Vulnerability

Summary

Impact: Tampering. Microsoft rating: Important. Not known to be exploited — Exploitation Less Likely. Customer action: Required.

Details

According to the CVSS metrics, successful exploitation of this vulnerability could lead to major loss of availability (A:H). What does that mean for this vulnerability?
An attacker can send specially crafted packets which could affect availability of the service and result in Denial of Service (DoS).

Security updates
10.0.17763.8644 — https://support.microsoft.com/help/5082123
10.0.20348.5020 — https://support.microsoft.com/help/5082142
10.0.26100.32690 — https://support.microsoft.com/help/5082063
10.0.25398.2274 — https://support.microsoft.com/help/5082060
10.0.14393.9060 — https://support.microsoft.com/help/5082198
6.2.9200.26026 — https://support.microsoft.com/help/5082127
6.3.9600.23132 — https://support.microsoft.com/help/5082126

Vulnerabilities 1

High 7.5

CVE-2026-26154

Windows Server Update Service (WSUS) Tampering Vulnerability

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

Microsoft Windows Server 2019 Windows Server 2019 (Server Core installation) Windows Server 2022 Windows

Apr 14, 2026

Revision history

2026-04-14 #1
Information published.

References

CVE-2026-26154 Windows Server Update Service (WSUS) Tampering Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26154
Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
Common Vulnerability Scoring System
https://www.first.org/cvss