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Windows Internet Information Services: Remote code execution due to race condition

CVE-2026-119961High 8.1

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Summary

A race condition (CWE-362, CWE-416) in Windows Internet Information Services (IIS) allows an attacker to execute code remotely over the network. The CVE record rates the CVSS score as 8.1 with high impact on confidentiality, integrity and availability. The CVE record lists no privileges required, but the attack complexity is high and the NVD analysis is still pending.

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, including Server Core (10.0.14393.0 before 10.0.14393.9688)
  • Windows Server 2019, including 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

  • Security update from Microsoft's November 2026 Patch Tuesday (published 2026-11-10).
  • Fixed builds according to the CVE record: 10.0.14393.9688 (1607/Server 2016), 10.0.17763.9487 (1809/Server 2019), 10.0.19044.7846 (21H2).
  • Fixed builds for other products are based on secondary sources and must be verified in the MSRC Security Update Guide.

Workaround

  • Unknown. No vendor-documented interim mitigation was found.
  • Until patched, restrict IIS exposure to the internet.

Exploitation

  • No confirmed in-the-wild exploitation at the time of writing (CISA SSVC: Exploitation none).
  • The CVSS vector uses exploit maturity E:U (unproven).
  • No public proof-of-concept or exploit code was found.

Our recommendation

  • Patch IIS servers on affected Windows builds first, prioritising internet-facing servers.
  • Verify the fixed build and KB number per product in the MSRC Security Update Guide before rollout.
  • Restrict IIS exposure to the internet until patched and check which servers run IIS.
  • Monitor IIS logs and watch for signs of exploitation, and plan for a possible change in the NVD assessment (authentication requirement is still open).

Information from Microsoft (Patch Tuesday November 2026)

Severity (Microsoft)
Critical
Impact
Remote code execution – Windows Internet Information Services
Status on Patch Tuesday
Neither exploited nor publicly disclosed
Exploitability assessment
Exploitation less likely
Product family
Windows, Windows ESU (Extended Security Updates)
Updates (KB)
KB5131291, KB5131085, KB5131096, KB5131090, KB5131087, KB5132061

Entry in the Microsoft Security Update Guide

Public exploits

PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.

Research sources

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, 01:37.

Original description (NVD)

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Internet Information Services allows an unauthorized attacker to execute code over a network.

NVD references (1)

Sources

The tracker combines official, freely usable data sources – updated continuously:

This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.

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