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Windows 10 21h2Operating system · Microsoft

CVE-2026-42906

MEDIUM · 5.5 CVSS v3.1 Published 2026-06-09
Fix available
A fix is available. Upgrade to 10.0.19044.7417 / 10.0.19045.7417 or later.
See remediation →
57/100
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
Exposure of sensitive information to an unauthorized actor in Windows Shell allows an authorized attacker to disclose information 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

This is a local information disclosure vulnerability in Windows Shell where an authorized local attacker can gain access to sensitive information they should not have access to. The vulnerability stems from improper handling of sensitive data within the Windows Shell component, potentially exposing file contents, user data, or system configuration details to a local user with standard privileges.

MitigationApply the relevant Microsoft security update for Windows Shell when released, or ensure systems are kept current with Windows Update. Verify that user permissions are appropriately restricted following the principle of least privilege.

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 21h2Operating system
Affected:< 10.0.19044.7417
Windows 10 22h2Operating system
Affected:< 10.0.19045.7417
Windows 11 23h2Operating system
Affected:< 10.0.22631.7219
Windows 11 24h2Operating system
Affected:< 10.0.26100.8655
Windows 11 25h2Operating system
Affected:< 10.0.26200.8655
Windows 11 26h1Operating system
Affected:< 10.0.28000.2269
Windows Server 2022Operating system
Affected:< 10.0.20348.5256
Windows Server 2025Operating system
Affected:< 10.0.26100.32995

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 version
    Open Command Prompt and run `winver` or `systeminfo | findstr /B /C:"OS Version"` to obtain the exact build number
    Affected if The displayed build number is lower than any of the following thresholds: Windows 10 21h2: 19044.7417, Windows 10 22h2: 19045.7417, Windows 11 23h2: 22631.7219, Windows 11 24h2: 26100.8655, Windows 11 25h2: 26200.8655, Windows 11 26h1: 28000.2269, Windows Server 2022: 20348.5256, Windows Server 2025
  2. Identify Windows edition and release
    Run `winver` or check System Properties to determine if the system is Windows 10 21h2, Windows 10 22h2, Windows 11 23h2, Windows 11 24h2, Windows 11 25h2, Windows 11 26h1, Server 2022, or Server 2025
    Affected if The system matches any of the affected product versions listed in the CVE and the build number is below the corresponding threshold
  3. Confirm Windows Shell component is present
    Verify the Windows Shell is running by checking that explorer.exe process is active in Task Manager or running `Get-Process | Where-Object {$_.ProcessName -eq "explorer"}` in PowerShell
    Affected if The Windows Shell (explorer.exe) is present and running, which is the default state for affected Windows installations

The system is affected if it runs any of the listed Windows 10 or Windows 11 versions, or Windows Server 2022/2025, with a build number lower than the specified threshold for that version.

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 10.0.19044.7417 / 10.0.19045.7417 / 10.0.20348.5256 or later
Fixed in 10.0.19044.741710.0.19045.741710.0.20348.5256
Interim mitigation

Apply the relevant Microsoft security update for Windows Shell when released, or ensure systems are kept current with Windows Update. Verify that user permissions are appropriately restricted following the principle of least privilege.

Recommended fix High confidence

Windows 10 21h2: build 10.0.19044.7417 or later | Windows 10 22h2: build 10.0.19045.7417 or later | Windows 11 23h2: build 10.0.22631.7219 or later | Windows 11 24h2: build 10.0.26100.8655 or later | Windows 11 25h2: build 10.0.26200.8655 or later | Windows 11 26h1: build 10.0.28000.2269 or later |

  1. 1. Identify the current Windows version and build number by running 'winver' or 'systeminfo' in Command Prompt
  2. 2. Determine which Windows release branch your system is on (e.g., 21h2, 22h2, 23h2, 24h2, 25h2, 26h1, Server 2022, or Server 2025)
  3. 3. Check if your current build number is less than the fixed version for your release branch
  4. 4. If vulnerable, apply Windows Updates: Open Settings > Windows Update > Check for updates
  5. 5. Alternatively, manually download and install the specific security update from the Microsoft Update Catalog matching your Windows version (e.g., KB5063119 for the relevant month)
  6. 6. Restart the system after updates are installed
  7. 7. Verify the fix by checking that the build number matches or exceeds the fixed version for your release branch
Caveat Standard Windows update carries minimal risk; ensure critical data is backed up before applying updates in production environments

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

Fix this in Windows 10 21h2 Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
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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-2026-42906 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