Microsoft Windows Hyper-V NT Kernel Integration VSP Use-After-Free Vulnerability
Microsoft Windows Hyper-V NT Kernel Integration VSP contains a use-after-free vulnerability that allows a local attacker to gain SYSTEM privileges.
- Vendor
- Microsoft
- Product
- Windows
- CVSS
- 7.8
- EPSS (exploit probability)
- 1.6%
- Status
- kev
- CISA patch-by (BOD 22-01)
- Added to KEV
Is CVE-2025-21334 being exploited?
Yes. CISA added CVE-2025-21334 to its Known Exploited Vulnerabilities catalog on . CISA only lists a CVE when it has reliable evidence of exploitation in the wild.
FIRST's EPSS model puts the probability of exploitation activity in the next 30 days at 1.6% (scored October 21, 2026).
- CISA KEV[ LISTED ]
- ENISA EUVD (exploited)[ — ]
- CIRCL KEV[ — ]
Catalog snapshot 2026-11-13. Full cross-catalog view: /kev-comparison
CVE-2025-21334 timeline
- Added to CISA KEVsame day as NVD
- Published to NVD
Every event links to its source. Catalog dates are each catalog's own; day offsets count from NVD publication. Data: JSON
What to do
CISA required actionApply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
US federal civilian agencies must remediate by (21 days after listing) under BOD 22-01. Everyone else: that deadline is a sensible upper bound, not a target. Vendor guidance and the NVD record are linked under Source above.
Other Microsoft Windows CVEs we track
| CVE / Vulnerability | Severity | CVSS | EPSS | Added to KEV |
|---|---|---|---|---|
| CVE-2026-96951 Microsoft Windows Command Injection Vulnerability | [ HIGH ] | 8.8 | 9.8% | |
| CVE-2026-85880 Microsoft Windows ALPC Heap Buffer Overflow Privilege Escalationwrite-up | [ HIGH ] | 7.8 | 0.4% | |
| CVE-2026-81963 Microsoft Windows Update Stack Link-Following Privilege Escalationwrite-up | [ HIGH ] | 7.8 | 7.1% | |
| CVE-2026-68820 Windows AFD WinSock Use-After-Free Privilege Escalationwrite-up | [ HIGH ] | 7.0 | 8.6% | |
| CVE-2008-4250 Microsoft Windows Buffer Overflow Vulnerability | [ CRITICAL ] | 9.8 | 98.8% | |
| CVE-2026-32202 Microsoft Windows Protection Mechanism Failure Vulnerability | [ MEDIUM ] | 4.3 | 71.3% | |
| CVE-2025-60710 Microsoft Windows Link Following Vulnerabilityransomware use | [ HIGH ] | 7.8 | 4.6% | |
| CVE-2023-36424 Microsoft Windows Out-of-Bounds Read Vulnerability | [ HIGH ] | 7.8 | 12.1% |