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Exploited vulnerability · CISA KEV

Is CVE-2025-21391 exploited? Yes: in CISA KEV since 11 Feb 2025

Gociux · Microsoft Windows · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2025-21391, Microsoft Windows Storage Link Following Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 11 Feb 2025, the day it was published. It affects Microsoft Windows. If you run it, CISA's required action is: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

exploitedYesCISA KEV · 11 Feb 2025
ransomwareNot knownno confirmed use
EPSSbelow top 10%lower predicted activity right now (it is still confirmed exploited)
severity7.1CVSS 3.1 · high
US federal due4 Mar 2025BOD 22-01 deadline

What it is

Microsoft Windows Storage contains a link following vulnerability that could allow for privilege escalation. This vulnerability could allow an attacker to delete data including data that results in the service being unavailable.

VendorMicrosoft (391 exploited CVEs in KEV)
ProductWindows
VulnerabilityMicrosoft Windows Storage Link Following Vulnerability
WeaknessCWE-59
Published11 Feb 2025
Added to KEV11 Feb 2025
Reported by (CNA)microsoft

What to do

  1. Check whether you run it. Look for Windows in your asset inventory, including appliances and cloud images. Stack check lists every exploited Microsoft CVE at once.
  2. Apply the fix. Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
  3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 11 Feb 2025.
  4. Get told next time. Email alerts when CISA adds a CVE for Microsoft.

Other exploited CVEs in Windows

References

Questions

Is CVE-2025-21391 being exploited?

Yes. CISA added CVE-2025-21391 to the Known Exploited Vulnerabilities catalog on 11 Feb 2025, which means there is reliable evidence of exploitation in the wild.

Is CVE-2025-21391 used in ransomware attacks?

CISA does not list known ransomware use for it. That can change, and exploitation alone is reason to fix it first.

How do I fix CVE-2025-21391?

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. Check Microsoft's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected Windows and watch it for signs of compromise.

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in February 2025 · Microsoft scorecard · act-now radar.

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