MSRC-CVE-2026-81963 — Windows Update Stack Elevation of Privilege Vulnerability

Summary

Impact: Elevation of Privilege. Microsoft rating: Important. Exploited according to Microsoft — Exploitation Detected. Customer action: Required.

Details

What privileges could be gained by an attacker who successfully exploited this vulnerability?
An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.

Security updates
10.0.26100.33438 — https://support.microsoft.com/help/5122871
10.0.26200.9445 — https://support.microsoft.com/help/5124008
10.0.22631.7582 — https://support.microsoft.com/help/5122880
10.0.28000.2954 — https://support.microsoft.com/help/5124012

Vulnerabilities 1

High 7.8

CVE-2026-81963 Exploited Public exploit

Windows Update Stack Elevation of Privilege Vulnerability

Improper link resolution before file access ('link following') in Windows Update Stack allows an authorized attacker to elevate privileges locally.

Microsoft Windows Server 2025 Windows Server 2025 (Server Core installation) Windows 11 Version 24H2 Windows

Sep 8, 2026
KEV Sep 8, 2026

Revision history

2026-10-07 #5
Updated an acknowledgement. This is an informational change only.
2026-10-06 #4
Updated an acknowledgement. This is an informational change only.
2026-09-15 #3
Updated an acknowledgement. This is an informational change only.
2026-09-11 #2
Updated an acknowledgement. This is an informational change only.
2026-09-08 #1
Information published.

References

CVE-2026-81963 Windows Update Stack Elevation of Privilege Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-81963
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