dbcve.org
Windows 10 1607Operating system · Microsoft

CVE-2026-20812

MEDIUM · 6.5 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 →
71/100
Remediation priority · Elevated
Remotely reachable 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
Improper input validation in Windows LDAP - Lightweight Directory Access Protocol allows an authorized attacker to perform tampering over a network.

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

Improper input validation in Windows LDAP (Lightweight Directory Access Protocol) allows an authorized attacker to perform tampering attacks over a network. This integrity-focused vulnerability stems from insufficient validation of input data within the LDAP implementation in Windows, potentially allowing manipulation of directory data or operations.

MitigationApply the relevant Microsoft Windows security update for this vulnerability to all affected Windows systems, particularly domain controllers and servers running LDAP services. Validate LDAP functionality post-patch.

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:< 10.0.14393.8783
Windows 10 1809Operating system
Affected:< 10.0.17763.8276
Windows 10 21h2Operating system
Affected:< 10.0.19044.6809
Windows 10 22h2Operating system
Affected:< 10.0.19045.6809
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 2016Operating system
Affected:< 10.0.14393.8783

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
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/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 version and build number
    Open Command Prompt or PowerShell and run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to obtain the exact Windows build number
    Affected if The build number falls below the safe thresholds: 14393.8783 (Win10 1607/Server 2016), 17763.8276 (Win10 1809), 19044.6809 (Win10 21h2), 19045.6809 (Win10 22h2), 22631.6491 (Win11 23h2), 26100.7623 (Win11 24h2), or 26200.7623 (Win11 25h2)
  2. Verify LDAP service status
    Open Services (services.msc) or run 'Get-Service | Where-Object {$_.DisplayName -like "*LDAP*"}' in PowerShell to check if the LDAP service is present and running
    Affected if The LDAP service is installed and running on the system
  3. Check LDAP client configuration
    Run 'reg query "HKLM\SYSTEM\CurrentControlSet\Services\LDAP"' in Command Prompt to query LDAP registry settings
    Affected if The LDAP registry key exists, indicating LDAP client functionality is enabled on the system
  4. Identify domain controller or LDAP server roles
    Run 'netdom query fsmo' or check Server Manager > Tools > Active Directory Users and Computers to determine if the system is a domain controller, or check for LDAP server role installation
    Affected if The system is a domain controller or runs an LDAP server role, making it directly exposed to network-based LDAP tampering attacks

A system is affected if it runs any of the listed Windows versions below the specified build numbers AND has LDAP client or server functionality enabled, with domain controllers and LDAP servers being the highest-risk targets.

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 / 10.0.19044.6809 or later
Fixed in 10.0.14393.878310.0.17763.827610.0.19044.6809
Interim mitigation

Apply the relevant Microsoft Windows security update for this vulnerability to all affected Windows systems, particularly domain controllers and servers running LDAP services. Validate LDAP functionality post-patch.

Recommended fix Moderate confidence

Microsoft Security Update containing CVE-2026-20812 patch (install via Windows Update)

  1. Open Windows Update Settings on the affected Windows system
  2. Click 'Check for updates' to fetch the latest security patches
  3. Locate the Microsoft security update containing the fix for CVE-2026-20812
  4. Install the update and restart the system if prompted
  5. Verify the system build number matches or exceeds the fixed version for your Windows edition (e.g., Windows 10 1607 should be 10.0.14393.8783 or later)
Caveat Standard Windows security update - no breaking changes expected for this patch

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

Fix this in Windows 10 1607 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
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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-2026-20812 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