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High · 7.8 Known exploited Public exploit CVE-2026-81963 EUVD-2026-73889GHSA-4j4j-2wjq-mxqj

Windows Update Stack Elevation of Privilege Vulnerability

Published Sep 8, 2026 · Updated Nov 10, 2026 · Assigned by microsoft

Vendor: Microsoft Product: Windows 11 version 23H2 Product: Windows 11 Version 24H2 Product: Windows 11 Version 25H2 Product: Windows 11 version 26H1 Product: Windows Server 2025 Product: Windows Server 2025 (Server Core installation) Platform: Windows

Description

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

Affected products

VendorProductAffectedFixed
Microsoft Windows 11 version 23H2 10.0.22631.0 – < 10.0.22631.7582 10.0.22631.7582
Microsoft Windows 11 Version 24H2 10.0.26100.0 – < 10.0.26100.9445 10.0.26100.9445
Microsoft Windows 11 Version 25H2 10.0.26200.0 – < 10.0.26200.9445 10.0.26200.9445
Microsoft Windows 11 version 26H1 10.0.28000.0 – < 10.0.28000.2954 10.0.28000.2954
Microsoft Windows Server 2025 10.0.26100.0 – < 10.0.26100.33438 10.0.26100.33438
Microsoft Windows Server 2025 (Server Core installation) 10.0.26100.0 – < 10.0.26100.33438 10.0.26100.33438

Public exploits

Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.

Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.

GitHub 2 repositories

Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.

Advisories 3

References