Windows: Use-after-free in Overlay Filter enables local privilege escalation

Summary

A use-after-free vulnerability in the Windows Overlay Filter component allows an authorized local attacker to elevate privileges. The advisory lists many Windows 10, Windows 11 and Windows Server builds, while the CVE record's CPE lists only Windows 10 1607. Exploitation requires an existing low-privileged account and high attack complexity, so the risk is mainly as a second stage after a user session has been obtained, for example through phishing or a stolen credential.

Affected

• Windows 10 1607: 10.0.14393.0 to before 10.0.14393.9612
• Windows 10 1809: 10.0.17763.0 to before 10.0.17763.9376
• Windows 10 21H2: 10.0.19044.0 to before 10.0.19044.7807
• Windows 10 22H2: 10.0.19045.0 to before 10.0.19045.7807
• Windows 11 23H2: 10.0.22631.0 to before 10.0.22631.7652
• Windows 11 24H2: 10.0.26100.0 to before 10.0.26100.9711
• Windows 11 25H2: 10.0.26200.0 to before 10.0.26200.9711
• Windows 11 26H1: 10.0.28000.0 to before 10.0.28000.3231
• Windows 11 26H2: 10.0.26300.0 to before 10.0.26300.9711
• Windows Server 2016 (including Server Core): 10.0.14393.0 to before 10.0.14393.9612
• Windows Server 2019 (including Server Core): 10.0.17763.0 to before 10.0.17763.9376
• Windows Server 2022: 10.0.20348.0 to before 10.0.20348.5761

Fixed in

• Fixed builds are listed per version in the affected section above. Install the October 13, 2026 security update from Microsoft.
• Windows 10 1607 fixed build 10.0.14393.9612 comes from mirrored data and must be verified on the MSRC page.
• Windows 10 1607 LTSB reached end of support on October 13, 2026. Whether the fix is available without Extended Security Updates (ESU) is unknown.

Workaround

Unknown. No vendor workaround was documented in the sources reviewed. Patching or upgrading is the only confirmed remedy.

Exploitation

• Microsoft: not publicly disclosed, not exploited, exploitability assessment 'Exploitation Less Likely'.
• CISA SSVC: exploitation none, automatable no, technical impact total.
• Not listed in CISA KEV. EPSS is below 1%.
• No public proof of concept found.

Our recommendation

• Inventory all Windows 10 1607 and Windows Server 2016 systems, since they are out of support.
• Apply the October 2026 security update to all listed Windows versions. For 1607 devices, verify on the MSRC page whether the fix is available and check ESU eligibility, or upgrade the device.
• Prioritise shared, multi-user, terminal server and devices with local staff accounts.
• Restrict local accounts and monitor for unexpected privilege changes.
• No action needed for systems that are already fully patched.

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-2026-83749 msrc.microsoft.com
• Microsoft Release Information learn.microsoft.com
• Vulners: CVE-2026-83749 vulners.com
• Vulners Rapid7: Microsoft Windows CVE-2026-83749 vulners.com
• OpenCVE: CVE-2026-83749 app.opencve.io
• Insentra: Windows 10 LTSB is ending www.insentragroup.com
• Wikipedia: Windows Server 2016 en.wikipedia.org
• Wikipedia: Windows 10 version history en.wikipedia.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 4 Nov 2026, 08:17.