dbcve.org
Windows 10 1809Operating system · Microsoft

CVE-2026-34340

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 Projected File System 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

A Use After Free (UAF) vulnerability in the Windows Projected File System (ProjFS) allows a locally authenticated attacker to manipulate memory after it has been freed, potentially achieving elevated privileges. The vulnerability stems from improper memory management in the Projected File System component.

MitigationApply the relevant Microsoft security update for Windows Projected File System when released; ensure systems are patched promptly per organizational patch management policy.

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 Windows version against affected builds
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Version"' and compare the build number to the affected ranges: 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), Server 2019 (10.0.17763.8755). Versions below these thresholds are affected.
    Affected if Installed Windows build number is lower than the specified threshold for that version branch
  2. Verify Projected File System feature is enabled
    Run 'Get-WindowsOptionalFeature -Online -FeatureName *ProjFS*' in PowerShell with admin rights, or check via DISM: 'dism /online /get-features /featurename:ProjectedFileSystem'
    Affected if The Projected File System feature (ProjFS) is enabled on the system
  3. Check for registered ProjFS providers
    Inspect registry key 'HKLM\SYSTEM\CurrentControlSet\Services\ProjFS\Parameters\Providers' for any registered provider GUIDs, or query with 'reg query "HKLM\SYSTEM\CurrentControlSet\Services\ProjFS\Parameters\Providers"'
    Affected if Any ProjFS providers are registered on the system

A system is affected if its Windows version is below the specified build thresholds AND the Projected File System component is enabled or has providers registered.

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 relevant Microsoft security update for Windows Projected File System when released; ensure systems are patched promptly per organizational patch management policy.

Recommended fix High 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. Check current Windows version by running 'winver' or 'systeminfo' in Command Prompt
  2. Open Windows Settings > Update & Security > Windows Update
  3. Click 'Check for updates' to download and install the latest security updates
  4. Alternatively, manually install the specific KB patch from Microsoft Update Catalog matching your Windows version
  5. Restart the system after updates are installed
  6. Verify the fix by checking that the installed build number matches or exceeds the fixed version for your Windows release
Caveat Standard Windows update risks apply - ensure compatibility testing for line-of-business applications before deploying broadly; some older software may require updates or workarounds after security patches

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
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.

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-2026-34340 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