How severe is CVE-2025-21391?

CVE-2025-21391 has a CVSS score of 7.1/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2025-21391?

Affected package information for CVE-2025-21391 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2025-21391?

No fixed version has been published for CVE-2025-21391 yet. Monitor the advisory for updates, apply mitigations recommended by the vendor, and use O3 Security to track when a fix becomes available in your stack.

Is CVE-2025-21391 actively exploited in the wild?

No public exploit code has been indexed for CVE-2025-21391 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2025-21391?

CVE-2025-21391 has an EPSS (Exploit Prediction Scoring System) score of 5.1%, placing it in the 90th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

Is CVE-2025-21391 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2025-21391 (Microsoft Windows Storage Link Following Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2025-02-11. CISA required all US federal civilian agencies to remediate this vulnerability by 2025-03-04. The required action was: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2025-21391?

CVE-2025-21391 is classified as CWE-59 (CWE-59). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Which products and versions are affected by CVE-2025-21391?

CVE-2025-21391 affects microsoft windows 10 21h2; microsoft windows 10 22h2; microsoft windows 10 1507; microsoft windows 10 1607, and 9 more product(s). Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2025-21391 published, and has it been updated?

CVE-2025-21391 was published on February 11, 2025 and was last updated on October 27, 2025. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2025-02-11 — agencies required to remediate by 2025-03-04

CVE-2025-21391

HIGH

Windows Storage Elevation of Privilege Vulnerability

Published

Feb 11, 2025

Updated

Oct 27, 2025

Affected

0 pkgs

Patched

None yet

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

5.1%probability of exploitation in next 30 days

Lower Risk90th percentile+0.35%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

Windows Storage Elevation of Privilege Vulnerability

Affected Products

13 products · 16 configurations

windows 10 21h2microsoft

< 10.0.19044.5487

range

windows 10 22h2microsoft

< 10.0.19045.5487

range

windows 10 1507microsoft

< 10.0.10240.20915

range

windows 10 1607microsoft

< 10.0.14393.7785

range

windows 10 1809microsoft

< 10.0.17763.6893

range

windows 11 22h2microsoft

< 10.0.22621.4890

range

Frequently Asked Questions

Windows Storage Elevation of Privilege Vulnerability

O3 Security · Impact-Aware SCA

Is CVE-2025-21391 in your stack?

O3 detects CVE-2025-21391 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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