CVE-2025-21391: Microsoft Windows Storage Link Following Vulnerability

What it is

Windows Storage Elevation of Privilege Vulnerability

Description quoted from the CVE record (assigned by microsoft, published 2025-02-11).

Weakness: CWE-59: Improper Link Resolution Before File Access (‘Link Following’)

How it can be exploited

Exploitable with local access with low attack complexity needing low privileges and no user interaction. Impact: confidentiality none, integrity high, availability high. CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H/E:F/RL:O/RC:C

CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: no. Technical impact: partial.

On CISA KEV since

2025-02-11

US federal deadline

2025-03-04

Ransomware use

Not known

Public exploit evidence (Exploit Observer)

Also known as: BDU:2025-02132, CNNVD-202502-1054, EUVD-2025-2452, GHSA-hq9p-wcjc-wqxg

Exploit Observer has no public exploit code that names this CVE or one of its aliases.

Research and write-ups (1)

• Research or write-up: https://www.rapid7.com/db/vulnerabilities/microsoft-windows-cve-2025-21391

Vulnerability databases and vendor advisories (9)

Catalogue entries, not exploit evidence.

• Vulnerability database or vendor advisory: https://access.redhat.com/security/cve/cve-2025-21391
• Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2025-2452
• Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-hq9p-wcjc-wqxg
• Vulnerability database or vendor advisory: https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2025-21391
• Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2025-21391
• Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-21391
• Vulnerability database or vendor advisory: https://www.cnnvd.org.cn/home/globalSearch?keyword=CNNVD-202502-1054
• Vulnerability database or vendor advisory: https://www.vicarius.io/vsociety/posts/cve-2025-21391-detect-microsoft-storage-vulnerability
• Vulnerability database or vendor advisory: https://www.vicarius.io/vsociety/posts/cve-2025-21391-mitigate-microsoft-storage-vulnerability

93 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS

0.023
some chance of attack soon

VEDAS

0.744
some exploit evidence

On CISA KEV

Yes, since 2025-02-11

Detection rule

Out of scope (local)

Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish.

Who is affected

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: microsoft windows_10_1507, microsoft windows_10_1607, microsoft windows_10_1809, microsoft windows_10_21h2, microsoft windows_10_22h2, microsoft windows_11_22h2, microsoft windows_11_23h2, microsoft windows_11_24h2, microsoft windows_server_2016, microsoft windows_server_2019.

How to fix it

Fixed versions stated in the CVE record: 10.0.10240.20915, 10.0.14393.7785, 10.0.17763.6893, 10.0.19044.5487, 10.0.19045.5487, 10.0.22621.4890, 10.0.22631.4890, 10.0.26100.3194, 10.0.20348.3207, 10.0.25398.1425.

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

Vendor guidance:

• Windows Storage Elevation of Privilege Vulnerability (vendor-advisory, patch)

How to detect it

This bug needs local access to exploit. VEDAS signatures cover remotely exploitable bugs for now, so there is no network rule or remote check for it. Patch it and watch your endpoint telemetry for unusual local activity.

References

Vendor advisories and patches

• Windows Storage Elevation of Privilege Vulnerability (vendor-advisory, patch)

Government sources

• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-21391 (government-resource)

Other databases

• CVE record (cve.org)
• NVD
• Exploit Observer

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.