CVE-2025-21334: Microsoft Windows Hyper-V NT Kernel Integration VSP Use-After-Free Vulnerability
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability
Description quoted from the CVE record (assigned by microsoft, published 2025-01-14).
Weakness: CWE-416: Use After Free
How it can be exploited
Exploitable with local access with low attack complexity needing low privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: no. Technical impact: total.
- On CISA KEV since
- 2025-01-14
- US federal deadline
- 2025-02-04
- Ransomware use
- Not known
Public exploit evidence (Exploit Observer)
Also known as: BDU:2025-00282, CNNVD-202501-1978, EUVD-2025-2399, GHSA-3hcq-fqcw-cvgf
Exploit Observer has no public exploit code that names this CVE or one of its aliases.
Research and write-ups (1)
- Research or write-up: https://www.rapid7.com/db/vulnerabilities/microsoft-windows-cve-2025-21334
Vulnerability databases and vendor advisories (7)
Catalogue entries, not exploit evidence.
- Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2025-2399
- Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-3hcq-fqcw-cvgf
- Vulnerability database or vendor advisory: https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2025-21334
- Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2025-21334
- Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-21334
- Vulnerability database or vendor advisory: https://www.cnnvd.org.cn/home/globalSearch?keyword=CNNVD-202501-1978
- Vulnerability database or vendor advisory: https://www.tenable.com/cve/CVE-2025-21334
57 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.
VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.
Live scores
- EPSS
- 0.016
some chance of attack soon - VEDAS
- 0.689
some exploit evidence - On CISA KEV
- Yes, since 2025-01-14
- Detection rule
- Out of scope (local)
Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish.
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| Microsoft Windows 10 Version 21H2 | from 10.0.19044.0 before 10.0.19044.5371 | Not stated |
| Microsoft Windows 10 Version 22H2 | from 10.0.19045.0 before 10.0.19045.5371 | Not stated |
| Microsoft Windows 11 version 22H2 | from 10.0.22621.0 before 10.0.22621.4751 | Not stated |
| Microsoft Windows 11 version 22H3 | from 10.0.22631.0 before 10.0.22631.4751 | Not stated |
| Microsoft Windows 11 Version 23H2 | from 10.0.22631.0 before 10.0.22631.4751 | Not stated |
| Microsoft Windows 11 Version 24H2 | from 10.0.26100.0 before 10.0.26100.2894 | Not stated |
| Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) | from 10.0.25398.0 before 10.0.25398.1369 | Not stated |
| Microsoft Windows Server 2025 | from 10.0.26100.0 before 10.0.26100.2894 | Not stated |
| Microsoft Windows Server 2025 (Server Core installation) | from 10.0.26100.0 before 10.0.26100.2894 | Not stated |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
Exploit Observer also maps it to: microsoft windows_10_21h2, microsoft windows_10_22h2, microsoft windows_11_22h2, microsoft windows_11_23h2, microsoft windows_11_24h2, microsoft windows_server_2022_23h2, microsoft windows_server_2025, microsoft_corp windows_server_2022,_23h2_edition_(server_core_installation), microsoft_corp windows_server_2025, microsoft_corp windows_server_2025_(server_core_installation).
How to fix it
Fixed versions stated in the CVE record: 10.0.19044.5371, 10.0.19045.5371, 10.0.22621.4751, 10.0.22631.4751, 10.0.26100.2894, 10.0.25398.1369.
CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Vendor guidance:
- Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability (vendor-advisory, patch)
How to detect it
This bug needs local access to exploit. VEDAS signatures cover remotely exploitable bugs for now, so there is no network rule or remote check for it. Patch it and watch your endpoint telemetry for unusual local activity.
References
Vendor advisories and patches
- Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability (vendor-advisory, patch)
Government sources
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-21334 (government-resource)
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.