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Microsoft Windows Hyper-V: Denial of service through race condition

CVE-2026-119385Medium 4.7

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Summary

A race condition in Windows Hyper-V allows an authorized local attacker to cause a denial of service. Affected are Windows 10, Windows 11 and Windows Server systems with the Hyper-V component. The attacker needs local access and valid low-privilege credentials, and the attack is considered difficult to carry out. Impact is limited to availability, such as a crash of the host or a Hyper-V service.

Affected

  • Windows 10 Version 1607, 1809, 21H2, 22H2
  • Windows 11 Version 23H2, 24H2, 25H2, 26H1, 26H2
  • Windows Server 2016, 2019, 2022 (including Server Core installations)
  • Windows Server 2025: affected, exact build unverified

Fixed in

Fixed in the November 2026 security updates. Builds according to the CVE record:

  • Windows 10 1607 / Server 2016: 10.0.14393.9688
  • Windows 10 1809 / Server 2019: 10.0.17763.9487
  • Windows 10 21H2 (labelled 19044) and 22H2 (19045): 10.0.19045.7846 / 10.0.19044.7846
  • Windows 11 23H2: 10.0.22631.7711
  • Windows 11 24H2 / Server 2025 (26100): 10.0.26100.9974, Server 2025 build unverified
  • Windows 11 25H2 / 26H2: 10.0.26200.9974 / 10.0.26300.9974
  • Windows 11 26H1: 10.0.28000.3501
  • Windows Server 2022: 10.0.20348.5870

Build numbers were not fully confirmed against the MSRC page and should be checked there.

Workaround

Unknown. No workaround is documented in the sources. The fix is the security update.

Exploitation

  • No known exploitation; not marked as exploited in the sources reviewed.
  • Rapid7 rates exploitation as less likely; no public disclosure.
  • No public proof of concept found.
  • CISA SSVC: exploitation none, automatable no.
  • Not checked directly against the CISA KEV catalogue.

Our recommendation

  • Install the November 2026 cumulative updates for all affected Windows and Windows Server systems as part of the regular patch cycle.
  • Prioritise Hyper-V hosts, especially those running several tenants or untrusted workloads.
  • Confirm the exact fixed builds on the MSRC page and the Microsoft Update Catalog before deployment.
  • Restrict local logon and administrative access to Hyper-V hosts.

Information from Microsoft (Patch Tuesday November 2026)

Severity (Microsoft)
Important
Impact
Denial of service – Windows Hyper-V
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, 20:52.

Original description (NVD)

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Hyper-V allows an authorized attacker to deny service locally.

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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