Microsoft Windows: 3 exploited vulnerabilities (CVE-2025-21333, CVE-2025-21334, CVE-2025-21335)

CVE-2025-21333: Microsoft Windows Hyper-V NT Kernel Integration VSP contains a heap-based buffer overflow vulnerability that allows a local attacker to gain SYSTEM privileges. CVE-2025-21334: Microsoft Windows Hyper-V NT Kernel Integration VSP contains a use-after-free vulnerability that allows a local attacker to gain SYSTEM privileges. CVE-2025-21335: Microsoft Windows Hyper-V NT Kernel Integration VSP contains a use-after-free vulnerability that allows a local attacker to gain SYSTEM privileges. Added to CISA KEV on 2025-01-14.

Why this severity: CVSS 7.8 (CNA, v3.1); actively exploited (CISA KEV)

Started

Jan 14, 2025

Closed

Jan 14, 2025

CVEs

CVE-2025-21333CVE-2025-21334CVE-2025-21335

• Microsoft
• Windows
• CISA KEV

Notes & caveats

Derived from CISA KEV JSON feed catalogVersion 2026.10.21. CVSS from the CVE record (cvelistV5). Exact affected/fixed version strings are not always in the KEV record; verify against the vendor advisory URL. startedAt uses dateAdded (exploitation may have begun earlier; many entries are older CVEs newly confirmed as exploited in 2025).