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Windows 10 1607Operating system · Microsoft

CVE-2026-54109

HIGH · 7.8 CVSS v3.1 Published 2026-07-14
Fix available
A fix is available. Upgrade to 10.0.14393.9339 / 10.0.17763.9020 or later.
See remediation →
80/100
Remediation priority · High
Zero-click 5 weeks old

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
Integer overflow or wraparound in Windows Resilient File System (ReFS) allows an authorized attacker to execute code locally.

In the news

Third-party coverage
Trending covered by 1 outlet this week · latest 1mo ago

Surfaced from public web coverage — external links open in a new tab.

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

Integer overflow vulnerability in Windows ReFS (Resilient File System) allows a local authorized attacker to execute arbitrary code. The vulnerability stems from improper integer handling in file system operations that can be exploited through specially crafted input.

MitigationApply Microsoft security updates for Windows ReFS when available; restrict local access to trusted users only as an interim defense; consider disabling ReFS if not required in environments where untrusted local users exist.

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 1607Operating system
Affected:< 10.0.14393.9339
Windows 10 1809Operating system
Affected:< 10.0.17763.9020
Windows 10 21h2Operating system
Affected:< 10.0.19044.7548
Windows 10 22h2Operating system
Affected:< 10.0.19045.7548
Windows 11 24h2Operating system
Affected:< 10.0.26100.8875
Windows 11 25h2Operating system
Affected:< 10.0.26200.8875
Windows 11 26h1Operating system
Affected:< 10.0.28000.2269< 10.0.28000.2525
Windows Server 2016Operating system
Affected:< 10.0.14393.9339

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 version against affected ranges
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to get the exact Windows build number. Compare the build number to the affected versions: 14393.9339 (Win10 1607/Server 2016), 17763.9020 (Win10 1809), 19044.7548 (Win10 21h2), 19045.7548 (Win10 22h2), 26100.8875 (Win11 24h2), 26200.8875 (Win11 25h2), 28000.2269/28000.2525 (Win11 26h1)
    Affected if The installed Windows build number is lower than the corresponding threshold for your Windows version
  2. Verify if ReFS file system is enabled
    Run 'fsutil fsinfo volumeinfo X:' (where X: is a drive letter) or 'fsutil fsinfo drivetype X:' to check each volume's file system type. ReFS volumes will display 'Resilient File System (ReFS)'
    Affected if Any mounted volume shows as ReFS (Resilient File System)
  3. Check for ReFS.sys driver loaded
    Run 'driverquery /v | findstr -i refs' to list the ReFS driver and its start type, or check via PowerShell: 'Get-ItemProperty -Path HKLM:\SYSTEM\CurrentControlSet\Services\Refs'
    Affected if The ReFS driver (refs.sys) is present and loaded on the system
  4. Enumerate all ReFS-formatted volumes
    Run 'Get-Volume | Where-Object {$_.FileSystem -eq "ReFS"}' in PowerShell to list all volumes using the ReFS file system
    Affected if The system has one or more volumes formatted with ReFS

You are affected if your Windows version is below the threshold AND ReFS file system is enabled or any ReFS-formatted volumes exist on the 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 10.0.14393.9339 / 10.0.17763.9020 / 10.0.19044.7548 or later
Fixed in 10.0.14393.933910.0.17763.902010.0.19044.7548
Interim mitigation

Apply Microsoft security updates for Windows ReFS when available; restrict local access to trusted users only as an interim defense; consider disabling ReFS if not required in environments where untrusted local users exist.

Recommended fix High confidence

Microsoft releases patches through Windows Update; the fixed builds are: Windows 10 1607: 10.0.14393.9339 | Windows 10 1809: 10.0.17763.9020 | Windows 10 21h2: 10.0.19044.7548 | Windows 10 22h2: 10.0.19045.7548 | Windows 11 24h2: 10.0.26100.8875 | Windows 11 25h2: 10.0.26200.8875 | Windows 11 26h1:

  1. Open Windows Settings and navigate to Update & Security > Windows Update
  2. Click 'Check for updates' to ensure you receive the latest security patches
  3. Alternatively, manually check Microsoft Update Catalog for the specific KB article related to this CVE (check msrc.microsoft.com for the corresponding KB number)
  4. Install the security update that addresses CVE-2026-54109
  5. Restart the system after applying the update
  6. Verify the update was successfully installed by checking Windows Update history
Caveat Standard Windows patching risks apply - test patches in staging environments before broad deployment

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

Fix this in Windows 10 1607 Scoped from the published advisory
  • Consultation8.0 h
  • Implementation24.0 h
  • Testing16.0 h
  • Review / QA8.0 h
56.0 hours of engineering $9,760
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Scan for this in your stack

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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-2026-54109 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