CVE-2006-5420
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 · uneditedKerio WinRoute Firewall 6.2.2 and earlier allows remote attackers to cause a denial of service (crash) via malformed DNS responses.
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 confidenceKerio WinRoute Firewall versions 6.2.2 and earlier contain a vulnerability in DNS response handling where malformed DNS packets can cause the firewall service to crash, resulting in denial of service.
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<= 6.2.2= 5.0.1= 5.0.2= 5.0.3= 5.0.4= 5.0.5= 5.0.6= 5.0.7= 5.0.8= 5.0.9= 5.1= 5.1.1CVSS 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
- Authentication
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- Partial
AV:N/AC:L/Au:N/C:N/I:N/A:P
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 checksWork through these to decide whether this CVE applies to you.
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Verify Kerio WinRoute Firewall is installedCheck for Kerio WinRoute Firewall in the list of installed programs via Windows Control Panel > Programs and Features, or look for the service named 'WinRoute Firewall' in Windows Services (services.msc)Affected if Kerio WinRoute Firewall is not present on the system, the system is not affected
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Identify the installed versionOpen the Windows Services panel, locate the WinRoute Firewall service, right-click and select Properties to view the executable path, or open the Kerio WinRoute Firewall administration console and check the About or version informationAffected if The displayed version matches <= 6.2.2, or equals 5.0.1, 5.0.2, 5.0.3, 5.0.4, 5.0.5, 5.0.6, 5.0.7, 5.0.8, 5.0.9, 5.1, or 5.1.1
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Confirm DNS service is enabledOpen the Kerio WinRoute Firewall administration console, navigate to the DNS configuration or Network Services section, and verify whether DNS forwarding or DNS proxy is enabledAffected if DNS forwarding or DNS proxy feature is enabled and the firewall is configured to process DNS responses
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Check if firewall service is runningOpen Windows Services (services.msc), locate the WinRoute Firewall service, and verify the Status column shows 'Running'Affected if The service is running and DNS handling is active, making the vulnerability exploitable
The system is affected if Kerio WinRoute Firewall is installed with a version <= 6.2.2 or any of the listed 5.x versions, and DNS forwarding/proxy is enabled and running.
Generated from the published advisory. Verify against your own configuration.
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 dataUpdate to a patched version of Kerio WinRoute Firewall (6.2.3 or later). If patches are unavailable, consider upgrading to a supported product version or implementing alternative firewall solutions.
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2006-5420 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2006-5420 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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