Microsoft Windows Message Queuing: Use-after-free allows local code execution

Summary

A use-after-free vulnerability (CWE-416) in the Queue Manager component of Windows Message Queuing (MSMQ) allows an authorized local attacker to execute code. The CVSS 3.1 base score is 7.8 (High) with a local attack vector, low privileges required and no user interaction. An attacker needs an existing low-privileged account or foothold on the system, so the main risk is privilege escalation and full compromise after an initial intrusion. The CVE title mentions Remote Code Execution, but the description and CVSS vector describe local exploitation only.

Affected

• Windows 10 Version 1607 (below 10.0.14393.9612)
• Windows 10 Version 1809 (below 10.0.17763.9376)
• Windows 10 Version 21H2 (below 10.0.19044.7807)
• Windows 10 Version 22H2 (below 10.0.19045.7807)
• Windows 11 Version 23H2 (below 10.0.22631.7652)
• Windows 11 Version 24H2 and 25H2 (below 10.0.26100.9711 and 10.0.26200.9711)
• Windows 11 Version 26H1 (below 10.0.28000.3231)
• Windows 11 Version 26H2 (below 10.0.26300.9711)
• Windows Server 2012 and 2012 R2 (below 6.2.9200.26434 and 6.3.9600.23470)
• Windows Server 2016 (below 10.0.14393.9612)

Note: The CPE data in the CVE record lists Windows 10 1607, and third-party sources differ on some builds. Verify the product table on the MSRC advisory.

Fixed in

• Install the October 2026 security updates for your Windows version. The fixed builds are the versions shown as the upper limit under affected.
• Windows 10 1607 and Server 2016: 10.0.14393.9612 (to be verified on MSRC; no KB number confirmed).
• Windows Server 2012 and 2012 R2 are listed as affected; verify the fixed build on MSRC.

Workaround

• No workaround is provided in the CVE record.
• If MSMQ is not required, disable or remove the Message Queuing feature to remove the attack surface. Test line-of-business applications first.

Exploitation

• Not listed in CISA KEV.
• CISA SSVC: Exploitation none, Automatable no, Technical Impact total.
• EPSS score: 0.00318.
• No public proof of concept found in research. This does not prove that none exists.

Our recommendation

• Patch affected systems with the October 2026 cumulative updates, starting with multi-user systems such as terminal servers, file servers and shared workstations.
• Confirm the exact fixed builds and KB numbers on the MSRC page, especially for Windows 10 1607, for which no KB number is confirmed.
• Check whether MSMQ is installed and disable it where it is not needed.
• Windows 10 Enterprise LTSB 2016 (1607) is reportedly reaching end of support on 13 October 2026 (unverified). Plan an upgrade.
• Monitor for suspicious local privilege escalation activity.

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-2026-85874 msrc.microsoft.com
• OpenCVE: CVE-2026-85874 app.opencve.io
• Vulners NVD mirror: CVE-2026-85874 vulners.com
• Vulners VulnCheck/CISA SSVC data: CVE-2026-85874 vulners.com
• Strix: CVE-2026-85874 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 2 Nov 2026, 01:52.