Windows Universal Disk Format File System Driver (UDFS): Heap-based buffer overflow

Summary

A heap-based buffer overflow in the Windows Universal Disk Format File System Driver (UDFS) allows an authorized local user to elevate privileges. The CVSS 3.1 base score is 7.8 (High), and the CNA-assigned CWE is CWE-122. An attacker needs a local logon with low privileges, such as a user account or malware already running on the system, before gaining SYSTEM rights. The vulnerability is not remotely exploitable.

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 and 26H2: 10.0.26200.0 and 10.0.26300.0 to before 10.0.26200.9974 and 10.0.26300.9974
• Windows 11 Version 26H1: 10.0.28000.0 to before 10.0.28000.3501
• Windows Server 2022: 10.0.20348.0 to before 10.0.20348.5870

Fixed in

• Install the Microsoft security update for November 2026 or later, which provides the fixed builds listed above.
• KB article numbers: Unknown.
• Verify the exact fixed build numbers in the Microsoft Security Update Guide before relying on them.

Workaround

Unknown.

Exploitation

• Known exploitation in the wild: Unknown (none found).
• Public proof of concept: none found.
• CISA SSVC: exploitation none, automatable no, technical impact total.

Our recommendation

• Patch all affected Windows 10, Windows 11 and Windows Server systems in the next regular update cycle, and prioritise multi-user systems, terminal servers and shared workstations.
• Replace or patch Windows 10 1607 and 1809 systems first, as they are end-of-life.
• Restrict local logons to trusted users and monitor for unusual privilege escalation on hosts with untrusted users.
• Check the Microsoft Security Update Guide for the official fixed builds.

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-2026-122984 msrc.microsoft.com
• CVE.org record CVE-2026-122984 (Microsoft as CNA) www.cve.org
• Strix AI CVE-2026-122984 (third-party aggregator, unverified) 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, 03:26.