Microsoft Windows Hyper-V: Local privilege escalation via heap buffer overflow
Summary
A heap-based buffer overflow in the Windows Hyper-V virtualization component allows an authorized local attacker to elevate privileges. Successful exploitation can affect confidentiality, integrity and availability, and the scope changes beyond the vulnerable component. The attacker needs local access and valid low-privileged credentials, and attack complexity is high. Systems without the Hyper-V role are not affected.
Affected
- 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 2022 before 10.0.20348.5870
- Windows Server 2025 (including Server Core) before 10.0.26100.33822
Fixed in
Microsoft November 2026 security update (Patch Tuesday). Fixed builds are listed per product under affected. KB numbers: Unknown. Check the MSRC advisory.
Workaround
Unknown. No Hyper-V-specific workaround was found in the sources reviewed.
Exploitation
No evidence of exploitation in the wild found. No public proof of concept found. CISA SSVC: exploitation none, not automatable, total technical impact.
Our recommendation
- Patch all Hyper-V hosts with the November 2026 update, together with the rest of the Patch Tuesday batch.
- Check that Windows Update is current on all hosts and verify the installed build against the MSRC table.
- Review who has local logon rights on Hyper-V hosts and restrict them to necessary accounts.
- Monitor hosts for unexpected privilege changes and suspicious local activity.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Critical
- Impact
- Elevation of privilege – 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)
- KB5131090, KB5131096, KB5131080, KB5131077, KB5132061, KB5132043
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Response Center: CVE-2026-113856 msrc.microsoft.com
- CVE.org: CVE-2026-113856 record www.cve.org
- Talos: Microsoft Patch Tuesday November 2026 blog.talosintelligence.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, 04:06.
Original description (NVD)
Heap-based buffer overflow in Windows Hyper-V allows an authorized attacker to elevate privileges 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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