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Windows Server 2016Operating system · Microsoft

CVE-2026-20818

MEDIUM · 6.2 CVSS v3.1 Published 2026-01-13
Fix available
A fix is available. Upgrade to 10.0.14393.8783 / 10.0.17763.8276 or later.
See remediation →
67/100
Remediation priority · Elevated
No privileges 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
Insertion of sensitive information into log file in Windows Kernel allows an unauthorized 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 · low confidence

This is a local information disclosure vulnerability in the Windows Kernel where sensitive information is being written to log files. A local, unauthorized attacker could potentially read these log files to gain access to sensitive data that should not be exposed.

MitigationApply available Microsoft security patches for affected Windows versions. In the interim, restrict local access to sensitive systems and monitor log file locations for unauthorized access.

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 Server 2016Operating system
Affected:< 10.0.14393.8783
Windows Server 2019Operating system
Affected:< 10.0.17763.8276
Windows Server 2022Operating system
Affected:< 10.0.20348.4648
Windows Server 2022 23h2Operating system
Affected:< 10.0.25398.2092
Windows Server 2025Operating system
Affected:< 10.0.26100.7623

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
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:L/AC:L/PR:N/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 Server version and build number
    Run 'winver' or 'systeminfo' from command prompt, or execute 'reg query "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion" /v CurrentBuild' to retrieve the build number
    Affected if The installed build number falls below 14393.8783 (Server 2016), 17763.8276 (Server 2019), 20348.4648 (Server 2022), 25398.2092 (Server 2022 23h2), or 26100.7623 (Server 2025)
  2. Identify Windows Server version family
    Run 'systeminfo | findstr /B /C:"OS Name"' to determine if the system is running Server 2016, 2019, 2022, or 2025
    Affected if The system is any of the affected Windows Server versions listed in the CVE with a build number below the corresponding threshold
  3. Locate kernel log files on the system
    Search common Windows log directories such as %SystemRoot%\System32\LogFiles, %SystemRoot%\Debug, and %SystemRoot%\Logs for newly created or recently modified log files that may contain kernel-generated entries
    Affected if Any log files exist in system directories that contain sensitive kernel information that should not be exposed to unauthorized users
  4. Review file permissions on log directories
    Use 'icacls' command on log directories (e.g., 'icacls C:\Windows\System32\LogFiles') to verify if standard users or non-privileged accounts have read access
    Affected if Log directories or files grant read permissions to standard users or unauthorized local accounts, allowing them to access sensitive information

The system is affected if it runs an affected Windows Server version with a build number below the fixed threshold and has log files accessible to unauthorized 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 10.0.14393.8783 / 10.0.17763.8276 / 10.0.20348.4648 or later
Fixed in 10.0.14393.878310.0.17763.827610.0.20348.4648
Interim mitigation

Apply available Microsoft security patches for affected Windows versions. In the interim, restrict local access to sensitive systems and monitor log file locations for unauthorized access.

Recommended fix High confidence

Windows Server 2016: 10.0.14393.8783 | Windows Server 2019: 10.0.17763.8276 | Windows Server 2022: 10.0.20348.4648 | Windows Server 2022 23h2: 10.0.25398.2092 | Windows Server 2025: 10.0.26100.7623

  1. Check current Windows Server version by running 'winver' or 'systeminfo'
  2. Open Windows Update and check for available updates
  3. Install all cumulative updates, ensuring the installed version meets or exceeds the fixed version
  4. Alternatively, download the specific KB update from Microsoft Update Catalog matching your server version
  5. Restart the server after applying updates
  6. Verify the installed version: Windows Server 2016 should be 10.0.14393.8783 or higher; Windows Server 2019 should be 10.0.17763.8276 or higher; Windows Server 2022 should be 10.0.20348.4648 or higher; Windows Server 2022 23h2 should be 10.0.25398.2092 or higher; Windows Server 2025 should be 10.0.26100.7623 or higher
Caveat Standard cumulative updates; test in non-production environment before broad deployment

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

Fix this in Windows Server 2016 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.

Scan for this in your stack

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dbcve dependency scanner

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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-2026-20818 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