CVE-2025-21333
Published: January 14, 2025
Official Description
Microsoft Windows Hyper-V NT Kernel Integration VSP contains a heap-based buffer overflow vulnerability that allows a local attacker to gain SYSTEM privileges.
CISA KEV Advisory
Microsoft Windows Hyper-V NT Kernel Integration VSP Heap-based Buffer Overflow Vulnerability
Microsoft Windows Hyper-V NT Kernel Integration VSP contains a heap-based buffer overflow vulnerability that allows a local attacker to gain SYSTEM privileges.
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Risk Analysis
This heap-based buffer overflow vulnerability in Microsoft Windows Hyper-V NT Kernel Integration VSP allows a local attacker to gain SYSTEM privileges. With an EPSS score of 0.77984 and its presence in CISA's KEV, this flaw is highly likely to be exploited and poses a significant risk for privilege escalation.
Active exploitation of this vulnerability has been observed in the wild, confirming its critical nature. Exploitation requires local access to the system.
Administrators should apply the latest security updates for Microsoft Windows Hyper-V. Implement strong access controls and limit local user privileges to mitigate the impact of successful exploitation.
Technical Analysis
CVE-2025-21333 requires local access, meaning attackers must already have a foothold on the target system.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
CISA has added CVE-2025-21333 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.
Affected Vendors & Products
Exploit & PoC Resources
All References (2)
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2025-21333 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
- !CISA KEV: Federal agencies must patch per BOD 22-01 timeline
- !Active exploitation confirmed — treat as P1