What is CVE-2025-21335?

CVE-2025-21335 is a high-severity vulnerability in Microsoft Windows 10 Version 21h2, classified under Use After Free. CVSS score: 7.8/10. Published 2025-01-14.

How severe is CVE-2025-21335?

High severity. CVSS v3 base score is 7.8 out of 10.

Is CVE-2025-21335 known to be exploited?

Yes. CVE-2025-21335 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-01-14), indicating it is being actively exploited. 2 public proof-of-concept repositories are indexed.

Use After Free in Microsoft Windows 10 Version 21h2

CVE-2025-21335

Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability

Vulnerability class: Use-After-Free

EPSS: 0.076 (92.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C.

Affected products

Microsoft Windows 10 Version 21h2 — versions 10.0.19044.0
Microsoft Windows 10 Version 22h2 — versions 10.0.19045.0
Microsoft Windows 11 Version 22h2 — versions 10.0.22621.0
Microsoft Windows 11 Version 22h3 — versions 10.0.22631.0
Microsoft Windows 11 Version 23h2 — versions 10.0.22631.0
Microsoft Windows 11 Version 24h2 — versions 10.0.26100.0
Microsoft Windows Server 2022, 23h2 Edition (Server Core Installation) — versions 10.0.25398.0
Microsoft Windows Server 2025 — versions 10.0.26100.0
Microsoft Windows Server 2025 (Server Core Installation) — versions 10.0.26100.0

Weakness classification (CWE)

CWE-416 — Use After Free

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2025-01-14. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2025-02-04.

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

Public proof-of-concept exploits

References

Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability (vendor-advisory, patch)

Frequently asked questions

What is CVE-2025-21335?: CVE-2025-21335 is a high-severity vulnerability in Microsoft Windows 10 Version 21h2, classified under Use After Free. CVSS score: 7.8/10. Published 2025-01-14.
How severe is CVE-2025-21335?: High severity. CVSS v3 base score is 7.8 out of 10.
Is CVE-2025-21335 known to be exploited?: Yes. CVE-2025-21335 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-01-14), indicating it is being actively exploited. 2 public proof-of-concept repositories are indexed.