Microsoft Windows Network File System: Information disclosure via improper access control

Summary

Improper access control in the Windows Network File System (NFS) component allows an authorized attacker to disclose information. The attacker needs a valid low-privilege account on an affected Windows client or server and must act locally. No user interaction is required and the attack complexity is low. Only confidentiality is affected, with high impact.

Affected

• Windows 10 Version 1607: 10.0.14393.0 to before 10.0.14393.9688
• 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 2016 (including Server Core): 10.0.14393.0 to before 10.0.14393.9688
• 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: not confirmed in the official record; verify against the MSRC advisory

Fixed in

• Install the November 2026 security update from Microsoft (Patch Tuesday, November 10, 2026).
• 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.

Workaround

• No workaround is documented in the sources reviewed. Unknown whether Microsoft lists one.
• If NFS features are not used on a system, disabling them reduces the attack surface (own measure, not a vendor recommendation).

Exploitation

• Not known to be exploited. CISA SSVC assessment: exploitation none, not automatable.
• No public proof of concept found.

Our recommendation

• Apply the November 2026 cumulative update to affected Windows systems, prioritising multi-user file servers and systems that use NFS.
• Check whether NFS client or server features are enabled and disable them where they are not needed.
• Review which accounts have local logon rights on affected hosts and remove unneeded accounts.
• Monitor for unusual local access to NFS shares and sensitive data.

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-2026-118736 msrc.microsoft.com
• CVE Record CVE-2026-118736 www.cve.org
• BleepingComputer: Microsoft November 2026 Patch Tuesday www.bleepingcomputer.com
• Strix AI: CVE-2026-118736 www.strix.ai

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, 16:45.