CVE-2025-21333
Actively exploited. CVE-2025-21333 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-01-14) — exploitation has been observed in the wild, and US federal agencies are required to remediate it under BOD 22-01. Treat patching as urgent.
Public exploit code is available. Proof-of-concept or working exploit code for CVE-2025-21333 is indexed in Exploit-DB and GitHub PoC. Expect opportunistic scanning and exploitation attempts — prioritize remediation.
Microsoft Windows Hyper-V NT Kernel Integration VSP contains a heap-based buffer overflow vulnerability that allows a local attacker to gain SYSTEM privileges.
CSIRTS triage
- What
- This component contains a heap-based buffer overflow vulnerability that allows a local attacker to gain SYSTEM privileges.
- Who is affected
- Local users with access to the affected system are at risk.
- Urgency
- Remediation is critical due to active exploitation and high severity.
- Action
- Install the latest security updates from Microsoft.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Exploitation confirmedAlready exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 95% of all EPSS-scored CVEs.
Exploit availability
Public exploit or proof-of-concept code for CVE-2025-21333 is indexed in these free datasets. Available exploit code raises real-world risk independent of the CVSS score.
- Exploit-DBA public exploit is published in the Exploit-DB archive.look it up ↗
- GitHub PoCPublic proof-of-concept repositories on GitHub reference this CVE.look it up ↗
Advisory coverage (1)
- criticalexploitedCVE-2025-21333: Microsoft Windows Hyper-V NT Kernel Integration VSP Heap-based Buffer Overflow Vulnerabilitycisa-kev · 2025-01-14
External references
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