Microsoft Windows: Use-after-free privilege escalation in Program Compatibility Assistant

Summary

A use-after-free flaw in the Windows Program Compatibility Assistant Service allows an authorized attacker to elevate privileges on the local system. The service runs with elevated rights, so a successful attack can lead to SYSTEM-level access. An attacker needs a local foothold and low privileges first, for example through malware or a stolen user session; the attack complexity is high (CVSS 3.1: 7.0, High).

Affected

• Windows 11 version 23H2: 10.0.22631.0 to below 10.0.22631.7652
• Windows 11 version 24H2: 10.0.26100.0 to below 10.0.26100.9711
• Windows 11 version 25H2: 10.0.26200.0 to below 10.0.26200.9711
• Windows 11 version 26H1: 10.0.28000.0 to below 10.0.28000.3231
• Windows 11 version 26H2: 10.0.26300.0 to below 10.0.26300.9711
• Windows Server 2022: 10.0.20348.0 to below 10.0.20348.5761
• Windows Server 2025 (including Server Core): 10.0.26100.0 to below 10.0.26100.33650
• Note: the CVE record lists more products than the CPE data (Windows 11 23H2 only).

Fixed in

• Windows 11 23H2: 10.0.22631.7652
• Windows 11 24H2: 10.0.26100.9711
• Windows 11 25H2: 10.0.26200.9711
• Windows 11 26H1: 10.0.28000.3231
• Windows 11 26H2: 10.0.26300.9711
• Windows Server 2022: 10.0.20348.5761
• Windows Server 2025: 10.0.26100.33650
• Confirm the knowledge base article numbers on the MSRC advisory before rollout.

Workaround

Unknown. No vendor-published workaround was found beyond patching.

Exploitation

• Microsoft's assessment: not publicly disclosed, not exploited, exploitation less likely.
• Microsoft states that no publicly available exploit code exists.
• CISA SSVC: exploitation none, not automatable, total technical impact.
• A third-party EPSS score of about 0.27% indicates low exploitation probability.
• No in-the-wild exploitation was found in the sources reviewed, but the source list is limited.

Our recommendation

• Install the October 2026 cumulative update on all affected Windows 11 and Windows Server systems.
• Check the fleet inventory for affected builds and prioritise endpoints where users open untrusted files and administrative rights are shared.
• Limit local administrator rights and monitor for suspicious privilege escalation on endpoints.
• Plan an upgrade for Windows 11 23H2 devices nearing end of servicing, and verify dates on Microsoft's lifecycle page.

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-2026-72969 msrc.microsoft.com
• CVE record (CNA JSON) via Vulners vulners.com
• Microsoft advisory mirror via Vulners vulners.com
• Strix CVE table www.strix.ai
• Rapid7 entry via Vulners (EPSS) vulners.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 4 Nov 2026, 08:48.