dbcve.org
Windows 10 1607Operating system · Microsoft

CVE-2026-40422

MEDIUM · 5.5 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 →
57/100
Remediation priority · Elevated
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
Use of uninitialized resource in Windows File Explorer allows an authorized attacker to disclose information locally.

In the news

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

This vulnerability in Windows File Explorer involves the use of an uninitialized resource (likely a memory variable or data structure) that can be leveraged by an authenticated local attacker to disclose sensitive information. The attack does not require elevated privileges and exploits how File Explorer handles memory during certain operations.

MitigationApply Microsoft security updates for Windows as they become available, as this is a Windows OS component vulnerability. Prioritize patching endpoint systems and verify File Explorer functionality post-update.

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
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
None
Availability
None

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

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 build number
    Run 'winver' from Run dialog or execute 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' in Command Prompt
    Affected if The build number is lower than the affected version for your Windows release (10.0.14393.9339 for 1607/Server 2016, 10.0.17763.9020 for 1809, 10.0.19044.7548 for 21h2, 10.0.19045.7548 for 22h2, 10.0.26100.8875 for 24h2, 10.0.26200.8875 for 25h2, or 10.0.28000.2269 for 26h1)
  2. Verify File Explorer executable version
    Right-click on explorer.exe in C:\Windows\, select Properties, and check the Details tab for File Version, or run 'powershell (Get-Item "C:\Windows\explorer.exe").VersionInfo'
    Affected if The File Version is not displayed or shows a version earlier than the corresponding Windows build number listed in the affected versions
  3. Confirm local user access
    Check for the presence of any local user accounts by running 'net user' in Command Prompt
    Affected if Any local user account exists on the system, as the vulnerability can be exploited by any authenticated local user without elevated privileges

You are affected if your Windows build number is lower than the specified threshold for your Windows release and File Explorer is accessible to local users.

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 as they become available, as this is a Windows OS component vulnerability. Prioritize patching endpoint systems and verify File Explorer functionality post-update.

Recommended fix High confidence

Install the appropriate Windows cumulative update for your specific version (1607/1809/21h2/22h2/24h2/25h2/26h1) containing the security fix for CVE-2026-40422

  1. Identify the current Windows version and build number by running 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"'
  2. For Windows 10 1607 and Windows Server 2016: Upgrade to build 10.0.14393.9339 or later via Windows Update or download the cumulative update from the Microsoft Update Catalog
  3. For Windows 10 1809: Upgrade to build 10.0.17763.9020 or later via Windows Update or Microsoft Update Catalog
  4. For Windows 10 21h2: Upgrade to build 10.0.19044.7548 or later via Windows Update or Microsoft Update Catalog
  5. For Windows 10 22h2: Upgrade to build 10.0.19045.7548 or later via Windows Update or Microsoft Update Catalog
  6. For Windows 11 24h2: Upgrade to build 10.0.26100.8875 or later via Windows Update
  7. For Windows 11 25h2: Upgrade to build 10.0.26200.8875 or later via Windows Update
  8. For Windows 11 26h1: Upgrade to build 10.0.28000.2269 or later via Windows Update
Caveat Standard Windows cumulative updateapply; no major breaking changes expected for this security patch

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

Fix this in Windows 10 1607 Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing4.0 h
  • Review / QA2.0 h
9.0 hours of engineering $1,540
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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-2026-40422 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