CVEs / CVE-2025-21334

CVE-2025-21334: Microsoft Windows Hyper-V NT Kernel Integration VSP Use-After-Free Vulnerability

Known exploited in the CISA KEV catalog since 14 Jan 2025
high 7.8 CVSS 3.1 (from the CNA)
EPSS 1.57% chance of exploitation in the next 30 days, higher than 75% of CVEs (30 Oct 2026)
Last changed at its sources 17 Jun 2026

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Summary

Microsoft Windows Hyper-V NT Kernel Integration VSP contains a use-after-free vulnerability that allows a local attacker to gain SYSTEM privileges.
CISA, Known Exploited Vulnerabilities catalog

Description

Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability
The CVE record, via NVD · published 14 Jan 2025 · NVD status: Analyzed

Affected and fixed versions

As stated by the CVE record (from the CNA)
Product	Affected	Fixed in
Microsoft Windows 10 Version 21H2	from 10.0.19044.0, before 10.0.19044.5371	10.0.19044.5371
Microsoft Windows 10 Version 22H2	from 10.0.19045.0, before 10.0.19045.5371	10.0.19045.5371
Microsoft Windows 11 version 22H2	from 10.0.22621.0, before 10.0.22621.4751	10.0.22621.4751
Microsoft Windows 11 version 22H3	from 10.0.22631.0, before 10.0.22631.4751	10.0.22631.4751
Microsoft Windows 11 Version 23H2	from 10.0.22631.0, before 10.0.22631.4751	10.0.22631.4751
Microsoft Windows 11 Version 24H2	from 10.0.26100.0, before 10.0.26100.2894	10.0.26100.2894
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation)	from 10.0.25398.0, before 10.0.25398.1369	10.0.25398.1369
Microsoft Windows Server 2025	from 10.0.26100.0, before 10.0.26100.2894	10.0.26100.2894
Microsoft Windows Server 2025 (Server Core installation)	from 10.0.26100.0, before 10.0.26100.2894	10.0.26100.2894

Exploitation

In CISA KEV since	14 Jan 2025
Due date for US federal agencies	4 Feb 2025
Used in ransomware campaigns	Unknown
Required action	Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Severity

CVSS 3.1	7.8 high `CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H` Scored by the CNA ([email protected])
Weakness	CWE-416

References

CVE-2025-21334 on NVD
CVE-2025-21334 in the CISA KEV catalog
https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2025-21334 (cited by CISA)
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21334 Patch, Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-21334 US Government Resource

Sources

Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.

This product uses data from the NVD API but is not endorsed or certified by the NVD.