Microsoft Windows NTFS: Out-of-bounds write allows local code execution

Summary

An out-of-bounds write in the Windows NTFS file system driver allows a local attacker with low privileges to execute code. Exploitation requires local access and a valid low-privileged account; the flaw is not directly reachable over the network. The CVSS 3.1 score is 7.8 (High), with high impact on confidentiality, integrity and availability.

Affected

• Windows 10 Version 1809 and Windows Server 2019 (including Server Core): builds before 10.0.17763.9376
• Windows 10 Version 21H2: builds before 10.0.19044.7807
• Windows 10 Version 22H2: builds before 10.0.19045.7807
• Windows 11 Version 23H2: builds before 10.0.22631.7652
• Windows 11 Version 24H2: builds before 10.0.26100.9711
• Windows 11 Version 25H2 and 26H2: builds before 10.0.26200.9711 and 10.0.26300.9711
• Windows 11 Version 26H1: builds before 10.0.28000.3231
• Windows Server 2022: builds before 10.0.20348.5761
• Windows Server 2025 (including Server Core): builds before 10.0.26100.33650

Fixed in

• Windows 10 Version 1809 and Windows Server 2019: 10.0.17763.9376 or later
• Windows 10 Version 21H2: 10.0.19044.7807 or later
• Windows 10 Version 22H2: 10.0.19045.7807 or later
• Windows 11 Version 23H2: 10.0.22631.7652 or later
• Windows 11 Version 24H2: 10.0.26100.9711 or later
• Windows 11 Version 25H2: 10.0.26200.9711 or later
• Windows 11 Version 26H1: 10.0.28000.3231 or later
• Windows 11 Version 26H2: 10.0.26300.9711 or later
• Windows Server 2022: 10.0.20348.5761 or later
• Windows Server 2025: 10.0.26100.33650 or later

Workaround

Unknown.

• No vendor-documented workaround found. Install the security update.

Exploitation

• Microsoft lists the vulnerability as not exploited (Exploited: No); exploit code maturity is unproven.
• CISA SSVC: exploitation none, not automatable.
• EPSS is about 0.003.
• No public proof of concept was found in the research; recheck before the next review.

Our recommendation

• Patch Windows 10 Version 1809 and Windows Server 2019 hosts in the October 2026 update cycle, starting with multi-user systems, terminal servers and other servers.
• Inventory all Windows hosts and identify systems that still run build 17763 or other affected builds.
• Confirm the KB number and the support lifecycle of your 1809 systems on the MSRC page and Microsoft's lifecycle page before deployment.
• Restrict local logon where possible and monitor affected hosts for privilege escalation attempts.

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-2026-83712 msrc.microsoft.com
• vulners.com: CVE-2026-83712 (CNA record copy) vulners.com
• OpenCVE: CVE-2026-83712 (CISA SSVC data) app.opencve.io
• Rapid7 via vulners.com: CVE-2026-83712 (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 2 Nov 2026, 03:16.