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Windows Server Update Service

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

Important CVSS 7.5 EPSS 0.01064 2026-04 archive

Executive Summary

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

Overview

7.5
CVSS HIGH
Important
MS Severity
Not Exploited
MS Exploit Status
Less Likely
MS Exploit Likelihood
Category Tampering
Released Apr 14 2026
Last Updated Apr 14 2026
Publicly Disclosed No
CISA KEV Not Listed
Known Exploits None Known
EPSS Score 0.01064 — 0.60241 percentile
NVD CVSS 7.5 HIGH — matches MSRC

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C
ATTACK VECTOR
Network
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
None
USER INTERACTION
None
SCOPE
Unchanged
CONFIDENTIALITY
None
INTEGRITY
None
AVAILABILITY
High
EXPLOIT CODE MATURITY
Unproven
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 6.5

EPSS Score

0.01064
probability of exploitation in the next 30 days
0.60241 percentile - updated 2026-06-21
View on FIRST.org

Affected Products

13 affected products
Product KB Article Severity Impact Restart Required
Windows Server 2012 5082127 (Monthly Rollup) Important Tampering Yes
Windows Server 2012 (Server Core installation) 5082127 (Monthly Rollup) Important Tampering Yes
Windows Server 2012 R2 5082126 (Monthly Rollup) Important Tampering Yes
Windows Server 2012 R2 (Server Core installation) 5082126 (Monthly Rollup) Important Tampering Yes
Windows Server 2016 5082198 (Security Update) Important Tampering Yes
Windows Server 2016 (Server Core installation) 5082198 (Security Update) Important Tampering Yes
Windows Server 2019 5082123 (Security Update) Important Tampering Yes
Windows Server 2019 (Server Core installation) 5082123 (Security Update) Important Tampering Yes
Windows Server 2022 5082142 (Security Update) Important Tampering Yes
Windows Server 2022 (Server Core installation) 5082142 (Security Update) Important Tampering Yes
Windows Server 2022, 23H2 Edition (Server Core installation) 5082060 (Security Update) Important Tampering Yes
Windows Server 2025 5082063 (Security Update) Important Tampering Yes
Windows Server 2025 (Server Core installation) 5082063 (Security Update) Important Tampering Yes

Patches

7 patches
Article Type Restart
5082127 Monthly Rollup Yes
5082126 Monthly Rollup Yes
5082198 Security Update Yes
5082123 Security Update Yes
5082142 Security Update Yes
5082060 Security Update Yes
5082063 Security Update Yes

Known Exploits

Acknowledgments

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