CVE-2025-21333
Microsoft Windows Hyper-V NT Kernel Integration VSP Heap-based Buffer Overflow Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 4 February 2025). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
Description
Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 10.07% probability · 96th percentile
- Public exploits
- 1 in Exploit-DB · first 16 September 2025
- CISA KEV
- Listed 14 January 2025 · due 4 February 2025
- Weakness
- CWE-122
- Affected
- microsoft/windows 10 21h2 · microsoft/windows 10 22h2 · microsoft/windows 11 22h2 · microsoft/windows 11 23h2 · microsoft/windows 11 24h2 · microsoft/windows server 2022 23h2 · microsoft/windows server 2025
- Source
- secure@microsoft.com
EPSS 10.1% since 30 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
CISA notes
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2025-21333 ; https://nvd.nist.gov/vuln/detail/CVE-2025-21333
Public exploits (1)
Entries in Exploit-DB that cite this CVE. Links go to the Exploit-DB page and to the file in the public repository; nothing is hosted here. A verified tick means the Exploit-DB team confirmed the exploit works against the stated version.
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21333Patch, Vendor Advisory
- https://www.exploit-db.com/exploits/52436Exploit, Third Party Advisory, VDB Entry
- https://www.vicarius.io/vsociety/posts/cve-2025-21333-elevated-privilege-exposure-in-windows-hyper-v-by-microsoft-detection-scriptMitigation, Third Party Advisory
- https://www.vicarius.io/vsociety/posts/cve-2025-21333-elevated-privilege-exposure-in-windows-hyper-v-by-microsoft-mitigation-scriptMitigation, Third Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-21333US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.