dbcve.org
Windows 10 1809Operating system · Microsoft

CVE-2023-21676

HIGH · 8.8 CVSS v3.1 Developing Published 2023-01-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
94/100
Remediation priority · Urgent
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
Windows Lightweight Directory Access Protocol (LDAP) Remote Code Execution Vulnerability

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

A remote code execution vulnerability exists in Windows Lightweight Directory Access Protocol (LDAP) implementation. The vulnerability allows an attacker to execute arbitrary code on affected Windows systems via specially crafted LDAP requests, likely through memory corruption or injection flaws in the LDAP service.

MitigationApply Microsoft security updates for CVE-2023-21676 to affected Windows systems, prioritizing domain controllers and systems with LDAP exposure.

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 1809Operating system
Affected:all versions
Windows 10 20h2Operating system
Affected:all versions
Windows 10 21h2Operating system
Affected:all versions
Windows 10 22h2Operating system
Affected:all versions
Windows 11 21h2Operating system
Affected:all versions
Windows 11 22h2Operating system
Affected:all versions
Windows Server 2019Operating system
Affected:all versions
Windows Server 2022Operating system
Affected:all versions

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
High
Integrity
High
Availability
High

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

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. Verify Windows version
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to identify the installed Windows version and build number
    Affected if The version matches any of the affected releases: Windows 10 1809, 20h2, 21h2, 22h2; Windows 11 21h2, 22h2; Windows Server 2019; or Windows Server 2022
  2. Confirm LDAP service is running
    Open Services console (services.msc) and locate the 'LDAP Client' or 'Active Directory Domain Services' service, or run 'Get-Service ldap*' in PowerShell
    Affected if An LDAP service is running or enabled on the system
  3. Check for Domain Controller role
    Run 'Get-ADDomain' in PowerShell (if AD module is installed) or check System Information for 'Domain Controller' role under 'System Role'
    Affected if The system is configured as a Domain Controller, as these are high-value targets for LDAP-based attacks
  4. Identify LDAP listening ports
    Run 'netstat -an | findstr "389 636"' or use PowerShell 'Get-NetTCPConnection -LocalPort 389,636' to check if LDAP ports are open and listening
    Affected if The system has LDAP ports (389 or 636) listening, indicating exposure to network-based LDAP requests
  5. Review recent LDAP-related events
    Open Event Viewer and navigate to 'Application and Services Logs > Directory Service' or run 'Get-WinEvent -FilterHashtable @{LogName='Directory Service';ID=1644} -MaxEvents 10' to look for unusual LDAP activity
    Affected if Suspicious LDAP query patterns or unexpected LDAP operation errors are logged, which may indicate exploitation attempts

The system is likely affected if it runs an affected Windows version and has LDAP services enabled or exposed, particularly if it functions as a Domain Controller.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply Microsoft security updates for CVE-2023-21676 to affected Windows systems, prioritizing domain controllers and systems with LDAP exposure.

Recommended fix Moderate confidence
  1. Check Windows Update for the latest security updates and install all pending updates
  2. If automatic updates are not available, search Microsoft Update Catalog for CVE-2023-21676 security update for your specific Windows version
  3. Download and install the appropriate security update (KB number) for your Windows version from the Microsoft Update Catalog
  4. Restart the affected system after installing the security update to ensure the patch takes effect
  5. Verify the update is installed by checking Installed Updates in Control Panel or running 'Get-HotFix' in PowerShell
Caveat Test LDAP-dependent applications and services after patching as the security update may modify LDAP behavior

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

Fix this in Windows 10 1809 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 help mitigating

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

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2023-21676 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2023-21676 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