Windows Update Stack: Information disclosure via integer underflow
Summary
Microsoft has fixed an integer underflow with out-of-bounds read in the Windows Update Stack of Windows 11 and Windows Server 2025. An authorized local user with low privileges can disclose information they should not see, with impact on confidentiality only. Exploitation requires a local logged-in account, CVSS 5.5 (Medium), and no exploitation is known.
Affected
- Windows 11 Version 24H2: 10.0.26100.0 to before 10.0.26100.9974
- Windows 11 Version 25H2: 10.0.26200.0 to before 10.0.26200.9974
- Windows 11 Version 26H1: 10.0.28000.0 to before 10.0.28000.3501
- Windows 11 Version 26H2: 10.0.26300.0 to before 10.0.26300.9974
- Windows Server 2025 (including Server Core): 10.0.26100.0 to before 10.0.26100.33822
Fixed in
- Windows 11 24H2, 25H2, 26H2: KB5132061 (10 Nov 2026), builds 26100.9974, 26200.9974, 26300.9974; requires servicing stack update 26100.9539 or later first
- Windows 11 26H1: KB unknown; fixed build 10.0.28000.3501
- Windows Server 2025: KB unknown; fixed build 10.0.26100.33822
Workaround
Unknown. No workaround is documented; install the November 2026 cumulative update.
Exploitation
- Not listed in CISA KEV; CISA SSVC: exploitation none, not automatable.
- Rapid7 rates exploitation as less likely; no public disclosure or public PoC found.
- Microsoft's temporal vector marks exploit maturity as Unproven.
Our recommendation
- Install the November 2026 cumulative update on affected systems, applying the required servicing stack update first.
- Identify Windows 11 23H2 Enterprise and Education machines, which reached end of updates on 10 Nov 2026 and will not receive this fix.
- Deploy with the regular update cycle rather than as an emergency change; the local attack vector and logged-in account requirement keep the priority low.
Information from Microsoft (Patch Tuesday November 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-122162 msrc.microsoft.com
- CVE.org record CVE-2026-122162 www.cve.org
- KB5132061 Windows 11 security update support.microsoft.com
- Rapid7 Patch Tuesday November 2026 www.rapid7.com
- BleepingComputer Patch Tuesday November 2026 www.bleepingcomputer.com
- Windows release health message center learn.microsoft.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 11 Nov 2026, 16:42.
Original description (NVD)
Integer underflow (wrap or wraparound) in Windows Update Stack allows an authorized attacker to disclose information 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.
Affected? We can help.
We check whether your systems are affected, install updates and close the gap – continuously with the System Health Checker if you wish.