CVE-2009-2730
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 · uneditedlibgnutls in GnuTLS before 2.8.2 does not properly handle a '\0' character in a domain name in the subject's (1) Common Name (CN) or (2) Subject Alternative Name (SAN) field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority.
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 confidencelibgnutls before version 2.8.2 fails to properly sanitize null byte characters in X.509 certificate Subject Alternative Name (SAN) and Common Name (CN) fields. An attacker can embed a \0 byte within a domain name (e.g., 'legitimate.com\0.malicious.com') to cause certificate validation libraries to truncate the string, allowing them to present a certificate appearing valid for a target domain while actually being issued for a different domain.
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<= 2.8.1= 1.0.16= 1.0.17= 1.0.18= 1.0.19= 1.0.20= 1.0.21= 1.0.22= 1.0.23= 1.0.24= 1.0.25= 1.1.13CVSS 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
- Partial
- Availability
- Partial
AV:N/AC:L/Au:N/C:P/I:P/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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Identify installed GnuTLS library versionRun `gnutls-cli --version` for the CLI tool, or check the library directly with `pkg-config --modversion gnutls` or `dpkg -l | grep gnutls` on Debian-based systems, or `rpm -q gnutls` on RHEL-based systemsAffected if The version shown is 2.8.1 or earlier, or exactly 1.0.16, 1.0.17, 1.0.18, 1.0.19, 1.0.20, 1.0.21, 1.0.22, 1.0.23, 1.0.24, 1.0.25, or 1.1.13
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Check linked GnuTLS library versionInspect the shared library file directly: `ls -l /usr/lib/libgnutls*` and `ldd <application_binary> | grep gnutls` to see which library version an application links againstAffected if The linked library version is 2.8.1 or earlier, or one of the vulnerable 1.x versions listed above
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Verify application uses GnuTLS for certificate validationReview application documentation or source code to confirm it uses libgnutls for TLS connections and X.509 certificate verification (look for gnutls_certificate_verify_peers2 or similar GnuTLS certificate verification functions)Affected if The application relies on GnuTLS for certificate validation and the library version is vulnerable
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Audit trusted CA certificatesExamine the system CA certificate store used by GnuTLS (typically /etc/ssl/certs/ca-certificates.crt or as configured via GNUTLS_SYSTEM_PRIORITY_FILE)Affected if GnuTLS is used with a trusted CA store and processes certificates from untrusted or attacker-controlled sources
If the GnuTLS library version is 2.8.1 or earlier, or matches any of the specific 1.0.x or 1.1.13 versions, and the system uses GnuTLS for certificate validation, the environment is vulnerable to null byte injection in X.509 certificate fields.
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 GnuTLS to version 2.8.2 or later, which properly rejects or handles null bytes in certificate domain names. Additionally, application-level validation should explicitly reject certificates containing null bytes in CN/SAN fields as a defense-in-depth measure.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2009-2730 — 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-2009-2730 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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- Version or environment caveats, and links to real fixes
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