dbcve.org
Windows 10 1809Operating system · Microsoft

CVE-2026-34337

HIGH · 7.0 CVSS v3.1 Published 2026-05-12
Fix available
A fix is available. Upgrade to 10.0.17763.8755 / 10.0.19044.7291 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
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 · moderate confidence

Use-after-free vulnerability in the Windows Cloud Files Mini Filter Driver (a kernel-mode component that manages cloud file caching). The flaw allows a locally authenticated attacker to manipulate freed memory and escalate privileges to SYSTEM level by exploiting improper object lifetime management in the driver.

MitigationApply the Microsoft security update for CVE-2026-34337 once released, as this is a kernel driver vulnerability that requires Microsoft-provided patches.

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:< 10.0.17763.8755
Windows 10 21h2Operating system
Affected:< 10.0.19044.7291
Windows 10 22h2Operating system
Affected:< 10.0.19045.7291
Windows 11 23h2Operating system
Affected:< 10.0.22631.7079
Windows 11 24h2Operating system
Affected:< 10.0.26100.8390
Windows 11 25h2Operating system
Affected:< 10.0.26200.8390
Windows 11 26h1Operating system
Affected:< 10.0.28000.2113
Windows Server 2019Operating system
Affected:< 10.0.17763.8755

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 your Windows version
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to obtain your Windows build number
    Affected if The build number falls below any of these thresholds: 17763.8755 (Windows 10 1809/Server 2019), 19044.7291 (Windows 10 21h2), 19045.7291 (Windows 10 22h2), 22631.7079 (Windows 11 23h2), 26100.8390 (Windows 11 24h2), 26200.8390 (Windows 11 25h2), or 28000.2113 (Windows 11 26h1)
  2. Verify the Cloud Files Mini Filter Driver is present
    Check for the driver file by running 'where /R C:\Windows\System32\drivers cloudfiles.sys' or list the drivers directory and search for cloudfiles.sys
    Affected if The file cloudfiles.sys exists on the system (the driver must be present for exploitation)
  3. Check the driver file version
    Right-click cloudfiles.sys, select Properties, then Details, and note the File Version; or run 'powershell (Get-Item "C:\Windows\System32\drivers\cloudfiles.sys").VersionInfo.FileVersion'
    Affected if The driver version is lower than the patched version for your Windows build (compare your version against the thresholds in the affected products list)
  4. Confirm the driver is loaded
    Run 'fltmc filters' or check in Device Manager under 'Non-Plug and Play Drivers' for Cloud Files Filter Driver
    Affected if The Cloud Files mini-filter driver shows as loaded or enabled (the driver must be active for the vulnerability to be exploitable)

You are affected if your Windows build is below the version thresholds AND the Cloud Files Mini Filter Driver (cloudfiles.sys) is present and 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 10.0.17763.8755 / 10.0.19044.7291 / 10.0.19045.7291 or later
Fixed in 10.0.17763.875510.0.19044.729110.0.19045.7291
Interim mitigation

Apply the Microsoft security update for CVE-2026-34337 once released, as this is a kernel driver vulnerability that requires Microsoft-provided patches.

Recommended fix Moderate confidence

Windows 10 1809: 10.0.17763.8755 | Windows 10 21h2: 10.0.19044.7291 | Windows 10 22h2: 10.0.19045.7291 | Windows 11 23h2: 10.0.22631.7079 | Windows 11 24h2: 10.0.26100.8390 | Windows 11 25h2: 10.0.26200.8390 | Windows 11 26h1: 10.0.28000.2113 | Windows Server 2019: 10.0.17763.8755

  1. Identify the current Windows build version by running 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"'
  2. Determine which Windows version family your system runs (Windows 10 1809, 10 21h2, 10 22h2, Windows 11 23h2, 24h2, 25h2, 26h1, or Windows Server 2019)
  3. For Windows 10 1809: Upgrade to build 10.0.17763.8755 or later
  4. For Windows 10 21h2: Upgrade to build 10.0.19044.7291 or later
  5. For Windows 10 22h2: Upgrade to build 10.0.19045.7291 or later
  6. For Windows 11 23h2: Upgrade to build 10.0.22631.7079 or later
  7. For Windows 11 24h2: Upgrade to build 10.0.26100.8390 or later
  8. For Windows 11 25h2: Upgrade to build 10.0.26200.8390 or later
Caveat Standard Windows cumulative update risks apply; ensure backups and compatibility testing for mission-critical systems

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

Fix this in Windows 10 1809 Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-34337 — 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-2026-34337 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