Vulnerability

CVE-2025-21335

High· 7.8KEVCVSS7.8EPSS8%

.rules3/5

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.

Threat signal

89/100

Severe

Severity

high

CVSS

7.8

EPSS

Active

KEV

CISA KEV — actively exploited

494d overdue

AffectedMicrosoft — Windows

Added to KEV

2025-01-14

Federal patch due (BOD 22-01)

2025-02-04

Required action (CISA verbatim)

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Vendor advisory + references

CISA description: “Microsoft Windows Hyper-V NT Kernel Integration VSP contains a use-after-free vulnerability that allows a local attacker to gain SYSTEM privileges.”

CVSS

v3.1Open in FIRST calculator →

7.8/ 10HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack VectorLocalRequires local access — shell, console, or local app.
Attack ComplexityLowNo special conditions — exploit works reliably.
Privileges RequiredLowStandard user privileges sufficient.
User InteractionNoneFully automated — no victim action needed.
ScopeUnchangedImpact contained to the vulnerable component.
Confidentiality ImpactHighTotal disclosure of sensitive data.
Integrity ImpactHighTotal compromise of integrity — full data modification possible.
Availability ImpactHighTotal loss of availability — full DoS possible.

EPSS

Exploit prediction · 30-day horizonFIRST.org →

7.65%

probability of exploitation in next 30 days

p92

higher than 92% of all CVEs

3-day trend↑ 0pp

Mid-pack — moderate exploitation likelihood.

Vendor VEX

No VEX statements published for CVE-2025-21335. Vendors publish VEX (Vulnerability Exploitability eXchange) to assert per-product whether a CVE is actually exploitable in their distribution.

SSVCAct

Active exploitation with total impact on essential/support systems

exploitation: active
automatable: no
impact: total
mission: support

Lifecycle

2025-01-14Added to CISA KEVransomware: Unknown
2025-01-14Published
2025-02-04Federal patch due (BOD 22-01)
2026-06-12Last modified1 source

No source-event history recorded yet. New revisions will appear here as ingestors re-fetch this CVE.