Windows vhdmp.sys: Use-after-free vulnerability enables local privilege escalation

Summary

A use-after-free flaw in the Windows Virtual Hard Disk miniport driver vhdmp.sys allows an authorized local user to elevate privileges. The CVSS vector requires high attack complexity and low privileges, with no user interaction. The flaw is not remotely exploitable, but it can be used as a step in an attack chain after an attacker has already gained a foothold.

Affected

• Windows 10 Version 1607 (builds before 10.0.14393.9688)
• Windows 10 Version 1809 (builds before 10.0.17763.9487)
• Windows 10 Version 21H2 (builds before 10.0.19044.7846)
• Windows 10 Version 22H2 (builds before 10.0.19045.7846)
• Windows 11 Version 23H2 (builds before 10.0.22631.7711)
• Windows 11 Version 24H2 (builds before 10.0.26100.9974)
• Windows 11 Version 25H2 (builds before 10.0.26200.9974)
• Windows 11 Version 26H1 (builds before 10.0.28000.3501)
• Windows 11 Version 26H2 (builds before 10.0.26300.9974)
• Windows Server 2016 and Server Core (builds before 10.0.14393.9688)
• Windows Server 2019 and Server Core (builds before 10.0.17763.9487)
• Windows Server 2022 (builds before 10.0.20348.5870)

Fixed in

• Install the November 2026 cumulative update for your Windows version (Patch Tuesday, 10 November 2026).
• 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.
• KB article numbers: Unknown.

Workaround

Unknown. No vendor workaround was identified in the sources. Patching is the practical fix.

Exploitation

• Exploitation in the wild for this CVE: Unknown. Talos reports that Microsoft notes one vulnerability disclosed this month was exploited, without naming it.
• CISA SSVC assessment: Exploitation none, Automatable no, Technical Impact total.
• CVSS temporal vector E:U (exploit code maturity unproven).
• Public proof of concept: none found.

Our recommendation

• Install the November 2026 cumulative update on all Windows 10, 11 and Server systems, prioritizing Remote Desktop and terminal servers and shared PCs.
• Check the MSRC exploitability section and the affected-product table for your builds.
• Review which standard users can mount VHD/VHDX files and restrict this where it is not required.
• Monitor for unusual privilege changes on endpoints and servers.
• The driver has had several use-after-free fixes in 2026, so keep it in regular patching.

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

• CVE Record CVE-2026-95989 www.cve.org
• Microsoft Security Update Guide CVE-2026-95989 msrc.microsoft.com
• Cisco Talos: Microsoft Patch Tuesday November 2026 blog.talosintelligence.com
• Qualys: Microsoft Patch Tuesday November 2026 blog.qualys.com
• Strix: CVE-2026-95989 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, 07:54.