Windows Projected File System: Elevation of privilege via stack-based buffer overflow

Summary

A stack-based buffer overflow in the Windows Projected File System (ProjFS) allows an authorized local attacker to elevate privileges. The attacker needs a valid local account with low privileges and no user interaction is required. Successful exploitation can give full control of the affected system (CVSS 3.1: 7.8, high impact to confidentiality, integrity and availability). The flaw is not reachable from the internet, but it matters once an attacker already has a local foothold.

Affected

• Windows 10 Version 1809 (10.0.17763.0 to before 10.0.17763.9487)
• Windows 10 Version 21H2 (10.0.19044.0 to before 10.0.19044.7846)
• Windows 10 Version 22H2 (10.0.19045.0 to before 10.0.19045.7846)
• Windows 11 Version 23H2 (10.0.22631.0 to before 10.0.22631.7711)
• Windows 11 Version 24H2 (10.0.26100.0 to before 10.0.26100.9974)
• Windows 11 Version 25H2 (10.0.26200.0 to before 10.0.26200.9974)
• Windows 11 Version 26H1 (10.0.28000.0 to before 10.0.28000.3501)
• Windows 11 Version 26H2 (10.0.26300.0 to before 10.0.26300.9974)
• Windows Server 2019 including Server Core (10.0.17763.0 to before 10.0.17763.9487)
• Windows Server 2022 (10.0.20348.0 to before 10.0.20348.5870)
• Windows Server 2025 including Server Core (10.0.26100.0 to before 10.0.26100.33822)
• Windows 10 Version 1607 and Windows Server 2016: Unknown.

Fixed in

• Fixed in Microsoft's November 2026 security release. Fixed builds: 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, 10.0.26100.33822.
• The exact KB article per product is not confirmed by the sources. Check the MSRC advisory.

Workaround

• No vendor workaround is documented.
• Unknown: whether disabling the optional ProjFS feature on systems that do not need it removes the exposure. Verify with MSRC guidance before relying on it.

Exploitation

• Not known to be exploited in the wild.
• No public proof-of-concept exploit found.
• CISA SSVC: exploitation none, not automatable, total technical impact.
• NVD status: Awaiting Analysis.

Our recommendation

• Install the November 2026 security updates on all affected Windows 10, Windows 11 and Windows Server systems, starting with multi-user servers, terminal servers and systems with local staff logons.
• Confirm the KB numbers and fixed builds on the MSRC advisory before rollout.
• Check whether Windows 10 devices are still supported or enrolled in Extended Security Updates.
• Limit local logon rights and review untrusted or service accounts with local access.
• Monitor for unexpected privilege escalation or new SYSTEM processes.

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 (CNA: Microsoft) www.cve.org
• MSRC Security Update Guide msrc.microsoft.com
• Strix CVE mirror (third-party) www.strix.ai
• Senserva KB tracker (third-party) senserva.com
• Tenable November 2026 Patch Tuesday analysis www.tenable.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 11 Nov 2026, 04:15.