Windows: Use-after-free in Windows Kernel allows privilege escalation

Summary

A use-after-free flaw (CWE-416) in the Windows kernel allows an authorized local attacker to elevate privileges. The CVSS scope is changed and the impact on confidentiality, integrity and availability is high, so a full compromise of the host is possible once an attacker has a foothold. An attacker needs a low-privilege local account or code already running on the system, so the flaw is not directly reachable from the internet.

Affected

• Windows 10 Version 1607: 10.0.14393.0 to before 10.0.14393.9688
• Windows 10 Version 1809: 10.0.17763.0 to before 10.0.17763.9487
• Windows 10 Version 21H2: 10.0.19044.0 to before 10.0.19044.7846
• Windows 10 Version 22H2: 10.0.19045.0 to before 10.0.19045.7846
• Windows 11 Version 23H2: 10.0.22631.0 to before 10.0.22631.7711
• 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 2016 (including Server Core): 10.0.14393.0 to before 10.0.14393.9688
• Windows Server 2019 (including Server Core): 10.0.17763.0 to before 10.0.17763.9487
• Windows Server 2022: 10.0.20348.0 to before 10.0.20348.5870

Fixed in

• Fixed in the November 2026 cumulative updates for the builds listed above (first fixed builds: 10.0.14393.9688, 10.0.17763.9487, 10.0.19044.7846, 10.0.19045.7846, 10.0.22631.7711, 10.0.26100.9974, 10.0.26200.9974, 10.0.28000.3501, 10.0.26300.9974, 10.0.20348.5870)
• Verify the KB number for each build in the Microsoft Security Update Guide, as the KB mapping could not be confirmed.

Workaround

Unknown.

Exploitation

• No evidence of exploitation in the wild found at publication.
• No public proof-of-concept exploit confirmed for this CVE.
• Microsoft's exploitability assessment: Exploitation More likely.
• CISA SSVC: Exploitation none, Automatable no, Technical Impact total.

Our recommendation

• Install the November 2026 security updates on all affected Windows hosts, prioritising terminal servers, multi-user systems and shared workstations.
• Limit interactive and local logons on multi-user systems and enforce least-privilege policies.
• Keep endpoint protection active and monitor for signs of local privilege escalation, especially after phishing or malware incidents.
• Verify the fixed builds and KB numbers in the Microsoft Security Update Guide before planning the rollout.

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-2026-109473 msrc.microsoft.com
• CVE.org CVE Record: CVE-2026-109473 www.cve.org
• Tenable: Microsoft November 2026 Patch Tuesday www.tenable.com
• Qualys: Microsoft Patch Tuesday November 2026 review blog.qualys.com
• Rescana: Microsoft Patch Tuesday November 2026 www.rescana.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, 04:25.