CVE-2025-21335
Windows Hyper-V NT Kernel Integration VSP Elevation of Privilege Vulnerability
do firstApply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Can a WAF block it? No. The attack needs local access to the machine, so a WAF is not on its path.
Also consider: patch
Based on the attack vector (local or physical access). We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Is CVE-2025-21335 being exploited?
Yes. CVE-2025-21335 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2025-21335?
CVE-2025-21335 is rated High with a CVSS score of 7.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2025-21335?
Yes. A fix has been recorded for CVE-2025-21335. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2025-21335 affect?
CVE-2025-21335 affects microsoft:windows_10_21h2, microsoft:windows_10_22h2, microsoft:windows_11_22h2, microsoft:windows_11_23h2, and 3 further products or versions. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
- affected>= 10.0.19044.0 and < 10.0.19044.5371
- affected>= 10.0.19045.0 and < 10.0.19045.5371
- affected>= 10.0.22621.0 and < 10.0.22621.4751
- affected>= 10.0.22631.0 and < 10.0.22631.4751
- affected>= 10.0.22631.0 and < 10.0.22631.4751
- affected>= 10.0.26100.0 and < 10.0.26100.2894
- affected>= 10.0.25398.0 and < 10.0.25398.1369
- affected>= 10.0.26100.0 and < 10.0.26100.2894
- affected>= 10.0.26100.0 and < 10.0.26100.2894
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.
cisa ssvc
- exploitation
- active
- automatable
- no
- technical impact
- total
Assessed by CISA 23 Jan 2025 (SSVC 2.0.3).
timeline
- 14 Jan 2025Added to CISA KEV (exploited in the wild)
- 14 Jan 2025Published · 1 day later
- 23 Jan 2025CISA SSVC assessment: exploitation active · 8 days later
- 4 Feb 2025CISA remediation due date (US federal agencies) · 12 days later
- 9 Jun 2026CVE record last updated · 491 days (about 1 year) later
- 2 Nov 2026Analysed by vulneraibility.com · 146 days (about 5 months) later
- Patchmsrc.microsoft.com /update-guide/vulnerability/CVE-2025-21335
- Linkcisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-21335
sources
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA KEV catalog: exploitation, date added, due date
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
- Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.