Microsoft Windows QWAVE service: Use-after-free leads to privilege escalation

Summary

A use-after-free flaw (CWE-416) in the Quality Windows Audio/Video Experience (QWAVE) service of Windows allows an authorized local user to elevate privileges. An attacker needs a local, low-privilege account or foothold, and the attack is rated as high complexity. Successful exploitation can fully compromise confidentiality, integrity and availability of the affected host.

Affected

• Windows 10 Version 1607 (10.0.14393.0 before 10.0.14393.9688)
• Windows 10 Version 1809 (10.0.17763.0 before 10.0.17763.9487)
• Windows 10 Version 21H2 (10.0.19044.0 before 10.0.19044.7846)
• Windows 10 Version 22H2 (10.0.19045.0 before 10.0.19045.7846)
• Windows 11 Version 23H2 (10.0.22631.0 before 10.0.22631.7711)
• Windows 11 Version 24H2 (10.0.26100.0 before 10.0.26100.9974)
• Windows 11 Version 25H2 (10.0.26200.0 before 10.0.26200.9974)
• Windows 11 Version 26H1 (10.0.28000.0 before 10.0.28000.3501)
• Windows 11 Version 26H2 (10.0.26300.0 before 10.0.26300.9974)
• Windows Server 2016 incl. Server Core (10.0.14393.0 before 10.0.14393.9688)
• Windows Server 2019 incl. Server Core (10.0.17763.0 before 10.0.17763.9487)
• Windows Server 2022 (10.0.20348.0 before 10.0.20348.5870)

Fixed in

• Install Microsoft's security update for CVE-2026-123389 from the MSRC Security Update Guide.
• Fixed builds per the CVE record: 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 numbers: Unknown.

Workaround

Unknown. No vendor workaround or mitigation was identified; patching is the remediation path.

Exploitation

• Not known to be exploited in the wild; CISA SSVC rates exploitation as none and automatable as no.
• No public proof of concept found.
• A third-party aggregator lists an EPSS score of 0.003 (not an official source).

Our recommendation

• Apply the Microsoft November 2026 security update to all affected Windows hosts, prioritising multi-user workstations and terminal or RDP servers.
• Verify the build numbers against the MSRC advisory before rollout.
• Check whether CVE-2026-69977 (reported as the same QWAVE flaw) is a separate CVE or a duplicate in your asset tracking.
• Monitor for public exploit reports after 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

• Microsoft Security Update Guide: CVE-2026-123389 msrc.microsoft.com
• CVE Record CVE-2026-123389 www.cve.org
• Qualys: Microsoft Patch Tuesday November 2026 review blog.qualys.com
• CWE-416: Use After Free cwe.mitre.org

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, 08:17.