Windows Hyper-V: Spoofing due to improper access control
Summary
A flaw in the Windows Hyper-V virtualisation platform allows improper access control, which enables spoofing. An attacker needs local access with high privileges and high attack complexity, so the flaw is not reachable from the internet. Microsoft fixed it on November 10, 2026. The exact spoofing mechanism is not described in the sources, and NVD analysis was still pending at publication.
Affected
- Windows 10 Version 1809 (before 10.0.17763.9487)
- Windows 10 Version 21H2 (before 10.0.19044.7846)
- Windows 10 Version 22H2 (before 10.0.19045.7846)
- Windows 11 Version 23H2 (before 10.0.22631.7711)
- Windows 11 Version 24H2 (before 10.0.26100.9974)
- Windows 11 Version 25H2 (before 10.0.26200.9974)
- Windows 11 Version 26H1 (before 10.0.28000.3501)
- Windows 11 Version 26H2 (before 10.0.26300.9974)
- Windows Server 2019 and Server Core installation (before 10.0.17763.9487)
- Windows Server 2022 (before 10.0.20348.5870)
- Windows Server 2025 and Server Core installation (before 10.0.26100.33822)
Fixed in
- Fixed in the Microsoft November 10, 2026 security updates.
- Confirm the exact build for each edition in the MSRC Security Updates table.
Workaround
Unknown. No vendor workaround was found. Patching is the intended remediation.
Exploitation
- No known exploitation.
- CISA SSVC: exploitation none, not automatable.
- Rapid7: Exploitation Less Likely, not publicly disclosed.
- No public proof of concept found.
Our recommendation
- Install the November 2026 cumulative updates on all Hyper-V hosts and Hyper-V-enabled clients.
- Confirm the installed build numbers against the MSRC table.
- Patch the other Hyper-V flaws released the same day, especially CVE-2026-119960 (Critical, local privilege escalation), in the same maintenance window.
- Review which accounts hold local administrator rights on hosts.
- Plan upgrades for Windows Server 2019 and Windows 10 1809, which carry a large patch backlog.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Spoofing – 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)
- KB5131085, KB5131096, KB5131090, KB5131087, KB5132061, KB5132043
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-119959 msrc.microsoft.com
- CVE Record CVE-2026-119959 www.cve.org
- Rapid7 Patch Tuesday November 2026 www.rapid7.com
- SANS ISC Diary storyid=33498 isc.sans.edu
- Senserva KB5131085 (Windows Server 2019) senserva.com
- Microsoft November 2026 Patch Tuesday (CybersecurityNews) cybersecuritynews.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, 18:28.
Original description (NVD)
Improper access control in Windows Hyper-V allows an authorized attacker to perform spoofing 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.
Affected? We can help.
We check whether your systems are affected, install updates and close the gap – continuously with the System Health Checker if you wish.