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Windows Internet Information Services: Denial of service vulnerability

CVE-2026-119909Medium 5.9

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Summary

Microsoft Windows Internet Information Services (IIS) contains an uncontrolled resource consumption flaw (CWE-401). An unauthenticated attacker on the network can make the service unavailable. Attack complexity is high, and the impact is limited to availability; code execution or data access is not described. Internet-facing IIS servers carry the greatest risk. Exploitation is not known, and no public proof of concept was found.

Affected

  • Windows 10 Version 1607 and Windows Server 2016 (including Server Core): builds 10.0.14393.0 before 10.0.14393.9688
  • Windows 10 Version 1809 and Windows Server 2019 (including Server Core): builds 10.0.17763.0 before 10.0.17763.9487
  • Windows 10 Version 21H2 and 22H2: builds 10.0.19044.0 before 10.0.19044.7846 and 10.0.19045.0 before 10.0.19045.7846
  • Windows 11 Version 23H2: builds 10.0.22631.0 before 10.0.22631.7711
  • Windows 11 Version 24H2, 25H2 and 26H2: builds 10.0.26100.0 before 10.0.26100.9974, 10.0.26200.0 before 10.0.26200.9974 and 10.0.26300.0 before 10.0.26300.9974
  • Windows 11 Version 26H1: builds 10.0.28000.0 before 10.0.28000.3501
  • Windows Server 2022: builds 10.0.20348.0 before 10.0.20348.5870
  • Note: the CNA record lists these builds; secondary sources disagree on some of them. Verify on the MSRC advisory.

Fixed in

  • Fixed in Microsoft's November 2026 Patch Tuesday security updates.
  • Exact KB numbers and fixed builds: see the MSRC advisory.

Workaround

Unknown.

  • No vendor workaround identified. Patching is the documented remedy.
  • Limit which hosts can reach the IIS service.

Exploitation

  • Not known to be exploited in the wild.
  • Rapid7 rates exploitation as less likely and reports no public disclosure.
  • No public proof of concept or exploit code found.

Our recommendation

  • Install the November 2026 Windows security updates on all affected Windows 10, Windows 11 and Windows Server systems, starting with internet-facing IIS servers.
  • Verify the affected builds and KB numbers in the MSRC advisory.
  • Check whether IIS is running and reachable from the internet, and restrict access where it is not required.
  • Monitor for changes in exploitation status and check NVD once analysis is complete.

Information from Microsoft (Patch Tuesday November 2026)

Severity (Microsoft)
Important
Impact
Denial of service – 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, 15:15.

Original description (NVD)

Uncontrolled resource consumption in Windows Internet Information Services allows an unauthorized attacker to deny service 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.

Affected? We can help.

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