Microsoft Windows 11: Use-after-free in Windows Update Service privilege escalation
Summary
A use-after-free flaw (CWE-416) in the Windows Update Service of Windows 11 and Windows Server 2025 allows an authorized local user to elevate privileges. The attacker needs a valid low-privilege account on the device, and exploitation is rated high-complexity. It is a post-compromise step and not reachable from the internet; the CVSS v3.1 base score is 7.0 (High).
Affected
- Windows 11 version 23H2: builds below 10.0.22631.7652
- Windows 11 version 24H2: builds below 10.0.26100.9711
- Windows 11 version 25H2: builds below 10.0.26200.9711
- Windows 11 version 26H1: builds below 10.0.28000.3231
- Windows 11 version 26H2: builds below 10.0.26300.9711
- Windows Server 2025 (including Server Core): builds below 10.0.26100.33650
- Windows 10 and other editions: Unknown.
Fixed in
- Windows 11 version 23H2: October 2026 cumulative update KB5126653 (build 10.0.22631.7652 or later), released October 13, 2026
- Other affected versions: install the October 2026 security update; verify the KB number in the MSRC entry.
Workaround
No workaround documented. Installing the October 2026 update is the mitigation.
Exploitation
- No evidence of exploitation in the wild for this CVE.
- CISA KEV status not confirmed.
- No public proof of concept found.
- CISA SSVC: exploitation none, automatable no, technical impact total.
Our recommendation
- Install the October 2026 cumulative update on all affected devices (version 23H2: build 10.0.22631.7652 or later). Microsoft marks the update as mandatory.
- Plan the upgrade of Windows 11 23H2 Enterprise and Education devices before end of servicing with the November 2026 update.
- Check the Microsoft lifecycle page for Home and Pro editions.
- Prioritize shared PCs and accounts that may be compromised, because exploitation requires local low-privilege access.
- Priority for most SMEs: medium.
Information from Microsoft (Patch Tuesday October 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-100200 msrc.microsoft.com
- Vulners CVELIST record CVE-2026-100200 vulners.com
- Microsoft release announcement MC1506288 mc.merill.net
- NinjaOne KB5126653 catalog entry www.ninjaone.com
- BleepingComputer: KB5127648 and KB5126653 cumulative updates released www.bleepingcomputer.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 4 Nov 2026, 10:02.
Original description (NVD)
Use after free in Windows Update Service allows an authorized attacker to elevate privileges locally.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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