CVE-2009-4123
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 · uneditedThe jruby-openssl gem before 0.6 for JRuby mishandles SSL certificate validation.
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 confidenceThe jruby-openssl gem before version 0.6 for JRuby improperly handles SSL certificate validation, likely failing to properly verify SSL/TLS certificate authenticity. This vulnerability could allow an attacker to perform man-in-the-middle attacks by presenting fraudulent certificates.
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< 0.6CVSS 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
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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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Verify jruby-openssl gem is installedRun `gem list jruby-openssl` in your JRuby environment or check your Gemfile for the jruby-openssl dependencyAffected if The gem is not present in the output or not listed in your Gemfile (not vulnerable because the gem is not in use)
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Determine jruby-openssl versionRun `gem list jruby-openssl` and note the version number shown, or inspect your Gemfile.lock for the jruby-openssl entryAffected if The displayed version is below 0.6 (for example, 0.5, 0.4, etc.)
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Confirm SSL/TLS connections are being madeReview your application code for usage of javax.net.ssl, OpenSSL::SSL, or any HTTPS URL handling that relies on jruby-openssl for certificate validationAffected if Your code makes SSL/TLS connections using jruby-openssl classes and the version is below 0.6
You are affected if jruby-openssl gem version below 0.6 is installed AND your application uses this gem to establish SSL/TLS connections.
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.
dbcve · scoped0.6
Upgrade jruby-openssl gem to version 0.6 or later to obtain proper SSL certificate validation. If upgrading is not immediately feasible, verify all SSL/TLS connections through alternative validation mechanisms or avoid using jruby-openssl for sensitive communications.
jruby-openssl version 0.6
- Verify the current version of jruby-openssl gem installed in your JRuby environment
- Upgrade the jruby-openssl gem to version 0.6 or later using the JRuby gem management system (e.g., gem install jruby-openssl -v 0.6 or gem update jruby-openssl)
- Verify the new version is installed correctly
- Test that SSL certificate validation is functioning properly in your application
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,096.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2009-4123 — 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-2009-4123 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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