dbcve.org
Windows 10 1607Operating system · Microsoft

CVE-2023-21546

HIGH · 8.1 CVSS v3.1 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 →
90/100
Remediation priority · Urgent
Remotely reachable 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
Windows Layer 2 Tunneling Protocol (L2TP) 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 · moderate confidence

This is a Remote Code Execution vulnerability in Windows Layer 2 Tunneling Protocol (L2TP), a VPN tunneling protocol. An attacker could exploit this to execute arbitrary code on affected Windows systems where L2TP is enabled, likely through specially crafted L2TP packets sent to the target system.

MitigationApply the relevant Microsoft security patches for CVE-2023-21546 to all affected Windows systems. If L2TP is not required, disable the L2TP service or block L2TP traffic at the network perimeter as a compensating control until patching is complete.

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:all versions
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 7Operating 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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/PR:N/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. Confirm Windows version is in affected list
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to identify the exact Windows version and build number. Compare against the affected versions: Windows 10 1607, 1809, 20h2, 21h2, 22h2; Windows 11 21h2, 22h2; Windows 7.
    Affected if The system runs any of the listed Windows versions without the security patch applied.
  2. Determine if L2TP is enabled
    Check for active L2TP interfaces by running 'netsh interface show interface' and look for interfaces with L2TP capability, or run 'Get-NetAdapter' in PowerShell and inspect the InterfaceDescription for RAS or VPN-related adapters.
    Affected if Any L2TP-enabled interface or VPN adapter is present and active on the system.
  3. Verify L2TP service status
    Run 'services.msc' and check the status of 'Routing and Remote Access (RRAS)' service, or run 'Get-Service RemoteAccess' in PowerShell. Also check 'll2tp' or 'L2TP' related services via 'sc query type= service state= all | findstr /i "l2tp"'.
    Affected if The Routing and Remote Access service or any L2TP-related service is running.
  4. Inspect L2TP VPN configurations
    Run 'netsh interface l2tp show state' to display current L2TP connection state, or check for L2TP VPN connections via 'Get-VpnConnection' in PowerShell.
    Affected if Any L2TP VPN connection profiles are configured on the system.
  5. Confirm patch status
    Check for installed security updates by running 'wmic qfe list' or 'Get-HotFix | Sort-Object InstalledOn' and look for the security update addressing CVE-2023-21546. The absence of this specific update means the system is vulnerable if L2TP is enabled.
    Affected if The security update for CVE-2023-21546 is not installed and L2TP is enabled or configured.

A system is affected if it runs an unpatched Windows version from the affected list AND has L2TP enabled, configured, or in use.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the relevant Microsoft security patches for CVE-2023-21546 to all affected Windows systems. If L2TP is not required, disable the L2TP service or block L2TP traffic at the network perimeter as a compensating control until patching is complete.

Fix this in Windows 10 1607 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-2023-21546 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