How severe is CVE-2025-21334?

CVE-2025-21334 has a CVSS 3.1 base score of 7.8 (HIGH). EPSS estimates a 1.6% probability of exploitation in the next 30 days. It is listed in the CISA Known Exploited Vulnerabilities catalog.

CVE-2025-21334: Windows Hyper-V NT Kernel Integration VSP Elevation

CISA Known Exploited Vulnerabilities

Microsoft Windows Hyper-V NT Kernel Integration VSP Use-After-Free Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.

Added to KEV

2025-01-14

Remediation due

2025-02-04

Required action
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

CISA notes
https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2025-21334 ; https://nvd.nist.gov/vuln/detail/CVE-2025-21334

Description

Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability

Severity

CVSS 3.1 · CNA7.8 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

SSVC · CISA-ADP

Exploitationactive

Automatableno

Technical impacttotal

Exploitation Context

as of October 17, 2026

All KEV statistics→

CISA added CVE-2025-21334 to the KEV catalog on the day its CVE record was published. The median for entries added in 2025 is 26 days.
It is one of 391 Microsoft entries in the CISA KEV catalog, and one of 39 added in 2025.
Its current EPSS score (1.6%) is higher than that of 6% of CISA KEV entries.

Affected Products

Vendor	Product	Affected versions
Microsoft	Microsoft Windows 10 Version 21H2	10.0.19044.0 to <10.0.19044.5371
Microsoft	Microsoft Windows 10 Version 22H2	10.0.19045.0 to <10.0.19045.5371
Microsoft	Microsoft Windows 11 version 22H2	10.0.22621.0 to <10.0.22621.4751
Microsoft	Microsoft Windows 11 version 22H3	10.0.22631.0 to <10.0.22631.4751
Microsoft	Microsoft Windows 11 Version 23H2	10.0.22631.0 to <10.0.22631.4751
Microsoft	Microsoft Windows 11 Version 24H2	10.0.26100.0 to <10.0.26100.2894
Microsoft	Microsoft Windows Server 2022, 23H2 Edition (Server Core installation)	10.0.25398.0 to <10.0.25398.1369
Microsoft	Microsoft Windows Server 2025	10.0.26100.0 to <10.0.26100.2894
Microsoft	Microsoft Windows Server 2025 (Server Core installation)	10.0.26100.0 to <10.0.26100.2894

References

1 Links

Vendor advisories

Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability

Record Details

Published

2025-01-14

Last updated

2026-06-09

Assigner (CNA)

microsoft

Credited to

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Tool categories

Fuzzing Binary Exploitation

CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.

CVE-2025-21334