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

• Severity: high (CVSS 7.1 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2025-02-11
• EPSS: 2.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-02-11 · updated 2026-09-24
• Weakness: CWE-59

Description

Windows Storage Elevation of Privilege Vulnerability

Affected products

• Microsoft Windows 10 Version 1507: before 10.0.10240.20915 — fixed in 10.0.10240.20915
• Microsoft Windows 10 1607: before 10.0.14393.7785 — fixed in 10.0.14393.7785
• Microsoft Windows 10: before 10.0.17763.6893 — fixed in 10.0.17763.6893
• Microsoft Windows 10: before 10.0.19044.5487 — fixed in 10.0.19044.5487
• Microsoft Windows 10: before 10.0.19045.5487 — fixed in 10.0.19045.5487
• Microsoft Windows 11: before 10.0.22621.4890 — fixed in 10.0.22621.4890
• Microsoft Windows 11: before 10.0.22631.4890 — fixed in 10.0.22631.4890
• Microsoft Windows 11: before 10.0.26100.3107 — fixed in 10.0.26100.3107
• Microsoft Windows Server 2016: before 10.0.14393.7785 — fixed in 10.0.14393.7785
• Microsoft Windows Server 2019: before 10.0.17763.6893 — fixed in 10.0.17763.6893
• Microsoft Windows Server 2022: before 10.0.20348.3148 — fixed in 10.0.20348.3148
• Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): before 10.0.25398.1425 — fixed in 10.0.25398.1425
• Microsoft Windows Server 2025: before 10.0.26100.3107 — fixed in 10.0.26100.3107

How to fix

Upgrade to a fixed version: Microsoft Windows 10 Version 1507 10.0.10240.20915; Microsoft Windows 10 1607 10.0.14393.7785; Microsoft Windows 10 10.0.17763.6893; Microsoft Windows 10 10.0.19044.5487; Microsoft Windows 10 10.0.19045.5487; Microsoft Windows 11 10.0.22621.4890; Microsoft Windows 11 10.0.22631.4890; Microsoft Windows 11 10.0.26100.3107; Microsoft Windows Server 2016 10.0.14393.7785; Microsoft Windows Server 2019 10.0.17763.6893; Microsoft Windows Server 2022 10.0.20348.3148; Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.1425. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21391
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-21391

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