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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 30 Dec 2025.
Windows 10 1809Operating system · Microsoft

CVE-2025-62221

HIGH · 7.8 CVSS v3.1 Published 2025-12-09
Fix available
A fix is available. Upgrade to 10.0.17763.8146 / 10.0.19044.6691 or later.
See remediation →
96/100
Remediation priority · Urgent
In the wild Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Use after free in Windows Cloud Files Mini Filter Driver allows an authorized attacker to elevate privileges locally.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A use-after-free vulnerability exists in the Windows Cloud Files Mini Filter Driver, a kernel-mode component responsible for cloud file operations. The memory corruption flaw can be exploited by a local authenticated attacker to achieve privilege escalation from a standard user context to elevated (SYSTEM) privileges.

MitigationApply the Microsoft security update for CVE-2025-62221 once released. As an interim control, organizations can audit local user permissions and restrict interactive logon rights on affected endpoints until the patch is deployed.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Windows 10 1809Operating system
Affected:< 10.0.17763.8146
Windows 10 21h2Operating system
Affected:< 10.0.19044.6691
Windows 10 22h2Operating system
Affected:< 10.0.19045.6691
Windows 11 23h2Operating system
Affected:< 10.0.22631.6345
Windows 11 24h2Operating system
Affected:< 10.0.26100.7392
Windows 11 25h2Operating system
Affected:< 10.0.26200.7392
Windows Server 2019Operating system
Affected:< 10.0.17763.8146
Windows Server 2022Operating system
Affected:< 10.0.20348.4467

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Windows build version
    Open Command Prompt and run 'winver' or 'systeminfo | findstr /B /C:"OS Version"' to obtain the full build number (e.g., 10.0.19045.XXXX)
    Affected if The build number is lower than any of these thresholds: 17763.8146 (Win10 1809/Server2019), 19044.6691 (Win10 21h2), 19045.6691 (Win10 22h2), 22631.6345 (Win11 23h2), 26100.7392 (Win11 24h2), 26200.7392 (Win11 25h2), or 20348.4467 (Server2022)
  2. Verify Cloud Files Mini Filter Driver is present
    Open Command Prompt and run 'fltmc filters' to list loaded filter drivers, or check for cloudfilt.sys in C:\Windows\System32\drivers\
    Affected if The Cloud Files filter driver (cloudfilt) appears in the loaded filters list or cloudfilt.sys exists on the system
  3. Confirm driver is actively loaded
    Run 'fltmc' without arguments to show filter driver status, or use 'sc query cloudfilt' to query the driver service state
    Affected if The Cloud Files Mini Filter Driver service state shows as RUNNING or the driver is listed as active in fltmc output

You are affected if your Windows build falls within the affected version ranges AND the Cloud Files Mini Filter Driver (cloudfilt.sys) is loaded on your system.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 10.0.17763.8146 / 10.0.19044.6691 / 10.0.19045.6691 or later
Fixed in 10.0.17763.814610.0.19044.669110.0.19045.6691
Interim mitigation

Apply the Microsoft security update for CVE-2025-62221 once released. As an interim control, organizations can audit local user permissions and restrict interactive logon rights on affected endpoints until the patch is deployed.

Recommended fix High confidence

Windows 10 1809: 10.0.17763.8146 | Windows 10 21h2: 10.0.19044.6691 | Windows 10 22h2: 10.0.19045.6691 | Windows 11 23h2: 10.0.22631.6345 | Windows 11 24h2: 10.0.26100.7392 | Windows 11 25h2: 10.0.26200.7392 | Windows Server 2019: 10.0.17763.8146 | Windows Server 2022: 10.0.20348.4467

  1. Open Settings > Update & Security > Windows Update and check for updates
  2. Install all cumulative updates containing the fix (KB references from Microsoft Security Response Center)
  3. Restart the system after applying updates
  4. Verify the installed version matches or exceeds the fixed build numbers for your Windows version using 'winver' or 'systeminfo'
Caveat Standard Windows cumulative update - review release notes for potential application compatibility issues

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Windows 10 1809 Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,840
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,544.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2025-62221 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-62221 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data