Windows COM: Local privilege escalation via stack-based buffer overflow

Summary

A stack-based buffer overflow in the Windows COM framework allows an authorized local attacker to elevate privileges on the affected system. The attacker needs a low-privileged local session, for example after phishing, malware or stolen credentials, and no user interaction is required. The impact on confidentiality, integrity and availability is rated high (CVSS 3.1: 7.8), and the risk is highest on multi-user systems such as terminal servers, shared workstations and file or application servers.

Affected

• Windows 10 Version 1607 (10.0.14393.0 before 10.0.14393.9688)
• Windows 10 Version 1809 (10.0.17763.0 before 10.0.17763.9487)
• Windows 10 Version 21H2 (10.0.19044.0 before 10.0.19044.7846)
• Windows 10 Version 22H2 (10.0.19045.0 before 10.0.19045.7846)
• Windows 11 Version 23H2 (10.0.22631.0 before 10.0.22631.7711)
• Windows 11 Version 24H2 (10.0.26100.0 before 10.0.26100.9974)
• Windows 11 Version 25H2 (10.0.26200.0 before 10.0.26200.9974)
• Windows 11 Version 26H1 (10.0.28000.0 before 10.0.28000.3501)
• Windows 11 Version 26H2 (10.0.26300.0 before 10.0.26300.9974)
• Windows Server 2016 incl. Server Core (10.0.14393.0 before 10.0.14393.9688)
• Windows Server 2019 incl. Server Core (10.0.17763.0 before 10.0.17763.9487)
• Windows Server 2022 (10.0.20348.0 before 10.0.20348.5870)
• Note: the secondary aggregator lists additional products, including Windows Server 2025, which the CNA record does not show. Verify against MSRC.

Fixed in

• Fixed in Microsoft's November 2026 security updates (Patch Tuesday).
• First fixed builds per the CNA record: Windows 10 1607/Server 2016 10.0.14393.9688; 1809/Server 2019 10.0.17763.9487; 21H2 10.0.19044.7846; 22H2 10.0.19045.7846; 11 23H2 10.0.22631.7711; 24H2 10.0.26100.9974; 25H2 10.0.26200.9974; 26H1 10.0.28000.3501; 26H2 10.0.26300.9974; Server 2022 10.0.20348.5870.
• The matching KB article could not be confirmed. Check the MSRC Security Update Guide.

Workaround

Unknown. No vendor workaround has been identified. Applying the security update is the only supported remediation.

Exploitation

• The CISA SSVC assessment lists exploitation as none and automatable as no.
• The CNA lists exploit code maturity as Unproven.
• No public proof of concept has been identified for this CVE.
• Release-level reports on the November 2026 updates name a different CVE as the exploited one. Check the MSRC flags and the CISA KEV catalogue to confirm the status of this CVE.

Our recommendation

• Include the fix in the November 2026 Windows patch cycle and prioritise multi-user systems, terminal servers and servers.
• Until patched, restrict local logon on shared hosts and limit local accounts to what is needed.
• Keep endpoint protection running and monitor for unexpected privilege escalation or new SYSTEM-level processes.
• Check the affected builds against your asset inventory and confirm the KB mapping on MSRC.

Public exploits iAttack code is publicly available (PoC on GitHub, Metasploit or Exploit-DB).

PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.

Research sources

• Microsoft Security Update Guide: CVE-2026-94531 msrc.microsoft.com
• CVE Record: CVE-2026-94531 www.cve.org
• Strix AI: CVE-2026-94531 (secondary, not verified against MSRC) www.strix.ai
• Rapid7: Patch Tuesday November 2026 www.rapid7.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, 03:12.