RubyApplication · Ruby Lang
CVE-2011-4121
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 OpenSSL extension of Ruby (Git trunk) versions after 2011-09-01 up to 2011-11-03 always generated an exponent value of '1' to be used for private RSA key generation. A remote attacker could use this flaw to bypass or corrupt integrity of services, depending on strong private RSA keys generation mechanism.
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 confidenceThe OpenSSL extension in Ruby (Git trunk) versions from September 1 to November 3, 2011 contained a bug where RSA key generation always used an exponent value of '1' instead of the proper value (typically 65537). This renders generated RSA keys completely insecure as exponent 1 produces trivial keys where the private key equals the public key, allowing trivial recovery of plaintext.
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
RubyApplication
>= 1.8.7.334, < 1.9.3CVSS 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
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/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 checksWork through these to decide whether this CVE applies to you.
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Check installed Ruby versionRun `ruby --version` or `ruby -v` to determine the Ruby interpreter versionAffected if Version is >= 1.8.7.334 and < 1.9.3
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Verify OpenSSL extension is loadedRun `ruby -ropenssl -e 'puts OpenSSL::VERSION'` to confirm OpenSSL extension is availableAffected if OpenSSL extension loads successfully in an affected Ruby version
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Test RSA key generation for exponent defectRun `ruby -ropenssl -e 'k = OpenSSL::PKey::RSA.new(2048); puts k.public_key.e'` and observe the exponent valueAffected if The exponent (e) equals 1 instead of 65537 (or another proper value)
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Inspect any existing RSA private keysUse `openssl rsa -in <keyfile> -text -noout` to view the public exponent in any previously generated RSA keysAffected if The public exponent displays as 1
You are affected if you use Ruby version 1.8.7.334 through 1.9.2 and have generated RSA keys using Ruby's OpenSSL extension during September-November 2011, as these keys have exponent 1 and provide essentially no security.
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 · scoped1.9.3
Organizations should identify and regenerate all RSA keys generated by affected Ruby versions during the vulnerable timeframe, as these keys provide essentially no security. Any encrypted data or signed content from this period should be re-encrypted/re-signed with new keys generated by patched Ruby versions.
Ruby 1.9.3 or later (preferably latest stable 2.x)
- 1. Identify current Ruby version by running `ruby --version`
- 2. Ensure all applications and scripts using this Ruby version are documented and can be tested
- 3. Create a backup of any critical data, configurations, and applications
- 4. Upgrade Ruby to version 1.9.3 or later (recommended: latest stable 1.9.x or 2.x branch)
- 5. Verify the OpenSSL extension is working correctly: run `ruby -ropenssl -e 'puts OpenSSL::VERSION'`
- 6. Test that RSA key generation produces proper keys: `ruby -ropenssl -e 'key = OpenSSL::PKey::RSA.new(2048); puts key.to_pem'
- 7. Regenerate any RSA keys that may have been generated by the vulnerable Ruby version
- 8. Redeploy the updated Ruby and verify all dependent applications function correctly
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Ruby
Scoped from the published advisory
- Consultation6.0 h
- Implementation12.0 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 $7,680.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-4121 — 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-2011-4121 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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