CVE-2009-0051
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 · uneditedZXID 0.29 and earlier does not properly check the return value from the OpenSSL DSA_verify function, which allows remote attackers to bypass validation of the certificate chain via a malformed SSL/TLS signature, a similar vulnerability to CVE-2008-5077.
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 · high confidenceZXID versions 0.29 and earlier fail to check the return value from OpenSSL's DSA_verify function during SSL/TLS certificate chain validation. When a malformed signature is presented, DSA_verify returns failure but ZXID continues processing as if validation passed, allowing attackers to bypass certificate validation through specially crafted signatures.
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<= 0.29= 0.1= 0.2= 0.3= 0.4= 0.5= 0.6= 0.7= 0.8= 0.9= 0.10= 0.11CVSS 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
- Partial
- Integrity
- None
- Availability
- None
AV:N/AC:L/Au:N/C:P/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 checksWork through these to decide whether this CVE applies to you.
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Identify ZXID versionRun 'zxid -v' or check the installed package version using your system package manager (dpkg -l zxid, rpm -qi zxid, or similar). If built from source, check the version string in the source archive or build logs.Affected if The installed version is 0.29 or earlier, or matches any of these: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.10, 0.11, or any version up to and including 0.29.
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Confirm SSL/TLS is in useInspect ZXID configuration files (typically zxid.conf or similar) for SSL, TLS, or HTTPS settings. Check if ZXID is configured to validate client or server certificates using OpenSSL DSA keys.Affected if ZXID is configured to perform SSL/TLS certificate validation with DSA-based certificates.
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Check for DSA certificate usageReview SSL/TLS configuration for references to DSA-based certificates or DSA certificate files. Look for certificate files using 'openssl x509 -in cert.pem -text' to verify the algorithm; DSA certificates will show 'Subject Public Key Algorithm: id-ecPublicKey' or DSA parameters.Affected if DSA-based certificates are being used for SSL/TLS validation in ZXID.
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Verify OpenSSL DSA_verify call is reachedThis vulnerability triggers when ZXID attempts to validate a certificate chain containing DSA signatures. The vulnerable code path is exercised when a peer presents a certificate during SSL/TLS handshake.Affected if SSL/TLS connections are established where ZXID validates a certificate chain containing DSA-signed certificates.
You are affected if ZXID version 0.29 or earlier is installed AND SSL/TLS certificate validation with DSA certificates is enabled and actively used.
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 dataUpgrade to a newer ZXID version that properly validates DSA_verify return values, or apply a patch to add proper error handling that rejects certificates when DSA_verify fails.
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2009-0051 — 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-2009-0051 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
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