Microsoft Windows EFS: Local denial of service through untrusted pointer dereference

Summary

An untrusted pointer dereference (CWE-822) in the Windows Encrypting File System (EFS) affects supported Windows 10, Windows 11 and Windows Server 2016 to 2022 systems. An authorized local attacker with low privileges and no user interaction can cause a denial of service and impair system availability. Remote exploitation is not possible according to the sources reviewed, and no exploitation or public proof of concept is known.

Affected

• Windows 10 Version 1607 and Windows Server 2016 (including Server Core): 10.0.14393.0 to before 10.0.14393.9688
• Windows 10 Version 1809 and Windows Server 2019 (including Server Core): 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 2022: 10.0.20348.0 to before 10.0.20348.5870

Fixed in

• Install the November 2026 Windows security updates for the affected versions.
• Fixed builds per the CVE record: 10.0.14393.9688 (1607, Server 2016), 10.0.17763.9487 (1809, Server 2019), 10.0.19044.7846 (21H2), 10.0.19045.7846 (22H2), 10.0.22631.7711 (23H2), 10.0.26100.9974 (24H2), 10.0.26200.9974 (25H2), 10.0.28000.3501 (26H1), 10.0.26300.9974 (26H2), 10.0.20348.5870 (Server 2022).
• Verify the Windows 11 24H2 and Server 2025 builds against the MSRC table, as a third-party source lists 10.0.26100.33822.

Workaround

Unknown. No Microsoft workaround or interim mitigation was found; the update is the only known remedy.

Exploitation

• Not known to be exploited in the wild, based on the sources reviewed.
• No public proof of concept found.
• CISA SSVC: exploitation none, not automatable, partial technical impact.
• CISA KEV status not verified.

Our recommendation

• Include the November 2026 Windows cumulative update in the regular patch cycle, prioritising multi-user systems such as terminal servers, RDS hosts and file servers that store EFS-encrypted data.
• Check the installed build numbers against the table above after patching.
• Restrict local logon on shared servers to necessary accounts.
• No emergency action appears necessary based on current information.

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 Response Center: CVE-2026-105527 msrc.microsoft.com
• CVE Record CVE-2026-105527 www.cve.org
• Senserva: KB5131080 summary senserva.com
• Rapid7: Patch Tuesday November 2026 www.rapid7.com
• Strix AI: CVE-2026-105527 www.strix.ai

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, 17:02.