CVE-2025-21335
Published 2025-01-14 · Updated 2026-09-24 · Source secure@microsoft.com
Summary
CVE-2025-21335 is a high-severity (CVSS 7.8) vulnerability in Microsoft Windows. CISA added it to the Known Exploited Vulnerabilities catalog on January 14, 2025, which means exploitation in the wild has been confirmed; US federal agencies had to remediate it by February 4, 2025. CISA does not currently list it as used in ransomware campaigns. Microsoft has 390 vulnerabilities in the KEV catalog, 117 of them linked to ransomware.
All 390 known-exploited Microsoft vulnerabilities →Description
Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability
CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CISA Known-Exploited Vulnerability
Product: Microsoft — Windows
Name: Microsoft Windows Hyper-V NT Kernel Integration VSP Use-After-Free Vulnerability
Date added: 2025-01-14 · Due: 2025-02-04
Required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.