PatchTheCVECVE-2025-21391: Microsoft Windows Storage Link Following Vulnerability
76
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HIGH 7.1EXPLOITEDWATCHLISTUPGRADEUPGRADEUPGRADE
CVE-2025-21391 is a high-severity flaw (CVSS 7.1) affecting windows 10 1507, windows 10 1607, windows 10 1809, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Windows Storage Elevation of Privilege Vulnerability
Why this priority
- High severity
- Exploited in the wild (CISA KEV)
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 7.1 (High) |
| Attack vector | Local |
| Attack complexity | Low |
| Privileges needed | Low |
| User interaction | None |
| EPSS exploit chance | 2.3% (top 17%) |
| CISA exploited list | Yes, fix due 2025-03-04 |
| Weakness | CWE-59 |
| Published | 2025-02-11 |
| Last modified | 2026-09-24 |
Publisher (CNA): Microsoft Corporation · Vendor: microsoft
Last updated 2026-09-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Exploited Added to the CISA Known Exploited Vulnerabilities list
- Published CVE record published
- Deadline CISA due date for US federal agencies to patch
- Updated Record last modified
microsoft windows 10 1507 UPGRADE
Affected: < 10.0.10240.20915
Fixed in: 10.0.10240.20915
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
microsoft windows 10 1607 UPGRADE
Affected: < 10.0.14393.7785
Fixed in: 10.0.14393.7785
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
microsoft windows 10 1809 UPGRADE
Affected: < 10.0.17763.6893
Fixed in: 10.0.17763.6893
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
microsoft windows 10 21h2 UPGRADE
Affected: < 10.0.19044.5487
Fixed in: 10.0.19044.5487
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
microsoft windows 10 22h2 UPGRADE
Affected: < 10.0.19045.5487
Fixed in: 10.0.19045.5487
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
microsoft windows 11 22h2 UPGRADE
Affected: < 10.0.22621.4890
Fixed in: 10.0.22621.4890
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
Exact fixes by distribution
Fedora 46 · opensips · FIXED · 4.0.3-1.fc46 · FEDORA-2026-6700a0026c · source
sudo dnf upgrade --advisory=FEDORA-2026-6700a0026c
Fedora ELN · ibus-typing-booster · FIXED · 2.31.3-1.eln159 · FEDORA-2026-c895c68d60 · source
sudo dnf upgrade --advisory=FEDORA-2026-c895c68d60
Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2025-21391?
windows 10 1507: upgrade to 10.0.10240.20915; windows 10 1607: upgrade to 10.0.14393.7785; windows 10 1809: upgrade to 10.0.17763.6893. Exact commands for each OS are on this page.
Is CVE-2025-21391 being exploited?
Yes. CVE-2025-21391 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.
What does CVE-2025-21391 affect?
CVE-2025-21391 affects windows 10 1507, windows 10 1607, windows 10 1809. Severity is high (CVSS 7.1). Windows Storage Elevation of Privilege Vulnerability
How urgent is CVE-2025-21391?
Priority 76/100. High severity; Exploited in the wild (CISA KEV); On your watchlist
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