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Windows 11 24h2Operating system · Microsoft

CVE-2025-59206

HIGH · 7.4 CVSS v3.1 Published 2025-10-14
Fix available
A fix is available. Upgrade to 10.0.26100.6899 / 10.0.26200.6899 or later.
See remediation →
79/100
Remediation priority · High
No privileges 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
Windows Resilient File System (ReFS) Deduplication Service Elevation of Privilege Vulnerability

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 · moderate confidence

An elevation of privilege vulnerability exists in the Windows Resilient File System (ReFS) Deduplication Service that allows an authenticated attacker to gain higher-level system privileges by exploiting the deduplication component.

MitigationApply Microsoft security updates for this vulnerability when available; in the interim, restrict access to the deduplication service and enforce least-privilege access controls.

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 11 24h2Operating system
Affected:< 10.0.26100.6899
Windows 11 25h2Operating system
Affected:< 10.0.26200.6899
Windows Server 2025Operating system
Affected:<= 10.0.26100.6899

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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/PR:N/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 version build number
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Version"' to retrieve the build number (e.g., 10.0.26100.xxxx)
    Affected if The build number is less than 10.0.26100.6899 for 24h2/Server 2025, or less than 10.0.26200.6899 for 25h2
  2. Verify if ReFS deduplication feature is installed
    Run 'Get-WindowsOptionalFeature -Online -FeatureName *Dedup*' in PowerShell to check if deduplication is installed as a Windows feature
    Affected if The deduplication feature is returned as Enabled or Available (the vulnerability requires this component to be present)
  3. Check for active deduplication volumes
    Run 'Get-DedupVolume -Volume <DriveLetter>' (e.g., Get-DedupVolume -Volume D:) to see if any volumes have deduplication enabled
    Affected if Any volumes show DedupEnabled as True (the exploit targets active deduplication on ReFS volumes)
  4. Verify ReFS filesystem is in use
    Run 'Get-Volume | Where-Object {$_.FileSystem -eq "ReFS"}' to list any volumes formatted with ReFS
    Affected if ReFS-formatted volumes exist in the environment (the vulnerability specifically targets ReFS deduplication)
  5. Check deduplication service status
    Run 'Get-Service -Name *Dedup*' to find and check the status of the deduplication service
    Affected if The deduplication service exists and is in a Running or Stopped state (the service must be present for the vulnerability to apply)

The system is affected only if the Windows build version falls within the affected ranges AND the deduplication feature or service is installed/enabled on ReFS volumes; otherwise the attack surface does not exist.

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 10.0.26100.6899 / 10.0.26200.6899 or later
Fixed in 10.0.26100.689910.0.26200.6899
Interim mitigation

Apply Microsoft security updates for this vulnerability when available; in the interim, restrict access to the deduplication service and enforce least-privilege access controls.

Recommended fix Moderate confidence

Windows 11 24h2 build 10.0.26100.6899 or later | Windows 11 25h2 build 10.0.26200.6899 or later | Windows Server 2025 build greater than 10.0.26100.6899

  1. Open Windows Settings on the affected system
  2. Navigate to Windows Update > Check for updates
  3. Install all available security updates for Windows
  4. Ensure the system builds meet or exceed the fixed versions: Windows 11 24h2 should be 10.0.26100.6899 or later, Windows 11 25h2 should be 10.0.26200.6899 or later, Windows Server 2025 should be greater than 10.0.26100.6899
  5. Restart the system after updates are installed
  6. Verify the installed version by running 'winver' or 'systeminfo' to confirm the build number matches or exceeds the fixed versions
Caveat Standard Windows update deployment risks apply - ensure backup/recovery plan in place before updating production systems

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

Fix this in Windows 11 24h2 Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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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-2025-59206 in production — separate from our analysis above.

No notes yet

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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