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Windows 11 23h2Operating system · Microsoft

CVE-2026-20838

MEDIUM · 5.5 CVSS v3.1 Published 2026-01-13
Fix available
A fix is available. Upgrade to 10.0.20348.4648 / 10.0.22631.6491 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
Generation of error message containing sensitive information in Windows Kernel allows an authorized attacker to disclose information locally.

In the news

Third-party coverage
Trending covered by 1 outlet this week · latest 7mo 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 is a local information disclosure vulnerability in the Windows Kernel where error messages inadvertently expose sensitive information. An authorized local attacker could exploit this to gain access to privileged or confidential data through crafted error message triggers.

MitigationApply the relevant Microsoft security patch for Windows Kernel when available. Until then, restrict local access to trusted only and monitor for anomalous error message 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 11 23h2Operating system
Affected:< 10.0.22631.6491
Windows 11 24h2Operating system
Affected:< 10.0.26100.7623
Windows 11 25h2Operating system
Affected:< 10.0.26200.7623
Windows Server 2022Operating system
Affected:< 10.0.20348.4648
Windows Server 2022 23h2Operating system
Affected:< 10.0.25398.2092
Windows Server 2025Operating system
Affected:< 10.0.26100.32230

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. Identify Windows version and build number
    Run 'winver' from command prompt, or use 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"', or check HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion in the registry
    Affected if The build number is lower than the affected versions: 22631.6491 (Win11 23h2), 26100.7623 (Win11 24h2), 26200.7623 (Win11 25h2), 20348.4648 (Server 2022), 25398.2092 (Server 2022 23h2), or 26100.32230 (Server 2025)
  2. Confirm Windows edition type
    Run 'systeminfo' or check System Properties to verify if the system is one of the affected editions: Windows 11 (23h2, 24h2, 25h2) or Windows Server 2022/2022 23H2/2025
    Affected if The system is Windows 11 or Windows Server edition and the build number from step 1 is below the corresponding threshold

The system is affected if it runs any of the listed Windows 11 or Windows Server versions with a build number lower than the specified threshold for that release.

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 10.0.20348.4648 / 10.0.22631.6491 / 10.0.25398.2092 or later
Fixed in 10.0.20348.464810.0.22631.649110.0.25398.2092
Interim mitigation

Apply the relevant Microsoft security patch for Windows Kernel when available. Until then, restrict local access to trusted only and monitor for anomalous error message behavior.

Recommended fix High confidence

Windows 11 23h2 build 10.0.22631.6491+ | Windows 11 24h2 build 10.0.26100.7623+ | Windows 11 25h2 build 10.0.26200.7623+ | Windows Server 2022 build 10.0.20348.4648+ | Windows Server 2022 23h2 build 10.0.25398.2092+ | Windows Server 2025 build 10.0.26100.32230+

  1. Check current Windows version by running `winver` or `systeminfo` in Command Prompt
  2. Open Settings > Windows Update > Check for updates
  3. Install all available updates, ensuring the kernel update containing the CVE-2026-20838 fix is applied
  4. Restart the system when prompted
  5. Verify the installed build number meets or exceeds the fixed version for your Windows edition (10.0.22631.6491 for 23h2, 10.0.26100.7623 for 24h2, 10.0.26200.7623 for 25h2, 10.0.20348.4648 for Server 2022, 10.0.25398.2092 for Server 2022 23h2, or 10.0.26100.32230 for Server 2025)
Caveat Standard Windows update; no breaking changes expected for this security patch

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

Fix this in Windows 11 23h2 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2026-20838 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