Windows Hyper-V: Denial of Service through uncontrolled resource consumption
Summary
Windows Hyper-V contains an uncontrolled resource consumption flaw (CWE-401, missing release of memory after its effective lifetime) that can be used to deny service. A local attacker with high privileges, such as an authorized user with access to the host or a VM administrator, can exhaust resources and make the affected system unavailable. Confidentiality and integrity are not affected, and the attack requires local access.
Affected
- Windows 11 23H2 (10.0.22631.0 to before 10.0.22631.7711)
- Windows 11 24H2 (10.0.26100.0 to before 10.0.26100.9974)
- Windows 11 25H2 (10.0.26200.0 to before 10.0.26200.9974)
- Windows 11 26H1 (10.0.28000.0 to before 10.0.28000.3501)
- Windows 11 26H2 (10.0.26300.0 to before 10.0.26300.9974)
- Windows Server 2022 (10.0.20348.0 to before 10.0.20348.5870)
- Windows Server 2025 and Server Core installation (10.0.26100.0 to before 10.0.26100.33822)
Fixed in
- Windows 11 23H2: 10.0.22631.7711 or later
- Windows 11 24H2: 10.0.26100.9974 or later
- Windows 11 25H2: 10.0.26200.9974 or later
- Windows 11 26H1: 10.0.28000.3501 or later
- Windows 11 26H2: 10.0.26300.9974 or later
- Windows Server 2022: 10.0.20348.5870 or later
- Windows Server 2025: 10.0.26100.33822 or later
Fix: November 2026 security update. KB numbers: Unknown.
Workaround
Unknown. No workaround has been published; apply the security update.
Exploitation
- No exploitation in the wild known.
- CISA SSVC: exploitation none, not automatable, partial technical impact.
- No public proof of concept found.
Our recommendation
- Install the November 2026 security update on all Hyper-V hosts, including Windows 11 Pro/Enterprise test and development machines and Windows Server hosts.
- Verify build numbers in the Microsoft Security Update Guide before rollout.
- Limit Hyper-V administration and VM administrator rights to trusted users.
- Include the update in the normal monthly Patch Tuesday cycle, with priority on multi-user systems.
Information from Microsoft (Patch Tuesday November 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-119955 msrc.microsoft.com
- CVE Record: CVE-2026-119955 www.cve.org
- Patch Tuesday coverage, November 2026 www.anoopcnair.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 11 Nov 2026, 14:47.
Original description (NVD)
Uncontrolled resource consumption 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:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
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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