CVE-2018-6517
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 · uneditedPrior to version 0.3.0, chloride's use of net-ssh resulted in host fingerprints for previously unknown hosts getting added to the user's known_hosts file without confirmation. In version 0.3.0 this is updated so that the user's known_hosts file is not updated by chloride.
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 chloride Ruby library prior to version 0.3.0 used net-ssh in a way that automatically added SSH host fingerprints for previously unknown hosts to the user's known_hosts file without user confirmation. This bypasses proper host key verification and could allow man-in-the-middle attacks by silently trusting new host keys.
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< 0.3.0CVSS 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
- None
- Integrity
- High
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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 if chloride gem is installedRun 'gem list chloride' or check Gemfile for 'chloride' dependencyAffected if chloride gem is present in the Ruby environment
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Determine installed chloride versionRun 'gem list chloride' to see the version number, or check the version specified in Gemfile.lockAffected if The version shown is less than 0.3.0 (for example, 0.2.0, 0.1.0, etc.)
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Verify SSH connections are being made through chlorideReview application code or configuration files that import and use the chloride library for SSH connectivityAffected if The application code invokes chloride to establish SSH connections, enabling the vulnerable net-ssh behavior
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Confirm automatic known_hosts modification is occurringMonitor the user's known_hosts file (typically ~/.ssh/known_hosts) for unexpected new entries after SSH connections via chloride, or enable SSH debug logging to observe the 'Host key added' behaviorAffected if New host keys appear in known_hosts without user prompts after establishing connections through chloride
A user is affected if chloride version below 0.3.0 is installed AND the application actively uses chloride to make SSH connections, allowing silent addition of host keys to known_hosts.
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 data0.3.0
Upgrade chloride to version 0.3.0 or later, which prevents automatic updating of the known_hosts file. Alternatively, ensure strict host key checking is enforced at the application level.
- Consultation1.0 h
- Implementation2.0 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-2018-6517 — 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-2018-6517 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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