dbcve.org
Windows 10 1809Operating system · Microsoft

CVE-2026-27926

HIGH · 7.0 CVSS v3.1 Published 2026-04-14
Fix available
A fix is available. Upgrade to 10.0.17763.8644 / 10.0.19044.7184 or later.
See remediation →
72/100
Remediation priority · Elevated
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
Concurrent execution using shared resource with improper synchronization ('race condition') 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 race condition vulnerability exists in the Windows Cloud Files Mini Filter Driver where concurrent access to shared resources lacks proper synchronization primitives, allowing a locally authorized attacker to exploit the timing window and elevate privileges to higher integrity levels.

MitigationApply the relevant Microsoft security update for this vulnerability; as an interim control, limit local access to trusted accounts and monitor for suspicious process behavior.

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:< 10.0.17763.8644
Windows 10 21h2Operating system
Affected:< 10.0.19044.7184
Windows 10 22h2Operating system
Affected:< 10.0.19045.7184
Windows 11 23h2Operating system
Affected:< 10.0.22631.6936
Windows 11 24h2Operating system
Affected:< 10.0.26100.8246
Windows 11 25h2Operating system
Affected:< 10.0.26200.8246
Windows 11 26h1Operating system
Affected:< 10.0.28000.1836
Windows Server 2019Operating system
Affected:< 10.0.17763.8644

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

CVSS:3.1/AV:L/AC:H/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 the installed Windows version
    Open Command Prompt or PowerShell and run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"'. Alternatively, run 'ver' in cmd to get the build number.
    Affected if The version is one of the affected products (Windows 10 1809, 10 21h2, 10 22h2, Windows 11 23h2/24h2/25h2/26h1, or Windows Server 2019) AND the build number is lower than the fixed version for that product line (17763.8644, 19044.7184, 19045.7184, 22631.6936, 26100.8246, 26200.8246, 28000.1836 respe
  2. Confirm the Cloud Files Mini Filter Driver is present
    Open an elevated Command Prompt and run 'fltmc filters' to list all loaded filter drivers. Look for 'CloudFiles' in the output.
    Affected if The CloudFiles filter driver is listed as loaded in the fltmc output, indicating the vulnerable component is present in the system.
  3. Check the CloudFiles driver file version
    Navigate to C:\Windows\System32\drivers\ and locate CloudFiles.sys. Right-click the file, select Properties, and view the Details tab for the File Version. Alternatively, run 'powershell "(Get-Item C:\Windows\System32\drivers\CloudFiles.sys).VersionInfo.FileVersion"' in an elevated prompt.
    Affected if The driver file exists and its version number is lower than the patched version corresponding to your Windows build, or the file cannot be found (driver may be part of a cumulative update not yet applied).

The system is affected if it runs a Windows version listed in the affected range AND the Cloud Files Mini Filter Driver is loaded, with a build or driver version below the fixed thresholds.

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 10.0.17763.8644 / 10.0.19044.7184 / 10.0.19045.7184 or later
Fixed in 10.0.17763.864410.0.19044.718410.0.19045.7184
Interim mitigation

Apply the relevant Microsoft security update for this vulnerability; as an interim control, limit local access to trusted accounts and monitor for suspicious process behavior.

Recommended fix High confidence

Apply the appropriate Microsoft security update: KB5055523 (Win 10 1809/Server 2019), KB5055537 (Win 10 21h2), KB5055538 (Win 10 22h2), KB5055525 (Win 11 23h2), KB5055519 (Win 11 24h2), KB5055520 (Win 11 25h2), KB5055521 (Win 11 26h1) - all to reach their respective fixed build versions

  1. Check current Windows build version by running 'winver' or 'systeminfo' in command prompt
  2. Identify your Windows version and build from the affected products list
  3. Apply the corresponding security update for your Windows version from Microsoft Update Catalog or Windows Update
  4. For Windows 10 1809/Windows Server 2019: Install KB5055523 (build 10.0.17763.8644)
  5. For Windows 10 21h2: Install KB5055537 (build 10.0.19044.7184)
  6. For Windows 10 22h2: Install KB5055538 (build 10.0.19045.7184)
  7. For Windows 11 23h2: Install KB5055525 (build 10.0.22631.6936)
  8. For Windows 11 24h2: Install KB5055519 (build 10.0.26100.8246)
Caveat Standard Windows security update; no expected breaking changes for most users, but test in staging if high-risk environment

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

Fix this in Windows 10 1809 Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,920
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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-2026-27926 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