RubyApplication · Ruby Lang
CVE-2018-16396
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 · uneditedAn issue was discovered in Ruby before 2.3.8, 2.4.x before 2.4.5, 2.5.x before 2.5.2, and 2.6.x before 2.6.0-preview3. It does not taint strings that result from unpacking tainted strings with some formats.
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 confidenceRuby fails to propagate taint flags when unpacking tainted strings using certain format specifiers in Array#pack and String#unpack methods. This allows attacker-controlled data to bypass taint-based security checks, potentially enabling injection or other attacks that rely on treating untrusted input as trusted.
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
>= 2.3.0, <= 2.3.7>= 2.4.0, <= 2.4.4>= 2.5.0, <= 2.5.1= 2.6.0
Ubuntu LinuxOperating system
= 14.04= 16.04= 18.04= 18.10
Debian LinuxOperating system
= 8.0= 9.0
Enterprise LinuxOperating system
= 6.0= 7.0= 7.4= 7.5= 7.6CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.0/AV:N/AC:H/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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Identify installed Ruby versionRun 'ruby --version' or 'ruby -v' to get the Ruby interpreter versionAffected if The version falls within 2.3.0-2.3.7, 2.4.0-2.4.4, 2.5.0-2.5.1, or 2.6.0
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Check for pack/unpack usage with tainted dataSearch codebase for calls to Array#pack or String#unpack methods, especially where input data may come from untrusted sources (user input, file reads, network data)Affected if Code uses pack or unpack methods on data that is or could be tainted (marked with Object#taint or derived from external sources)
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Test taint propagation behaviorRun a test script: 'ruby -e "s = 'test'.taint; result = s.unpack('M'); puts result.first.tainted?"' - the result should be tainted but is not in vulnerable versionsAffected if The unpack operation does not preserve the taint flag on the output (result shows .tainted? == false when input was tainted)
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Verify format specifiers in useReview which format specifiers are used with pack/unpack - the vulnerability triggers with certain specifiers that fail to propagate taintAffected if Code uses vulnerable format specifiers (such as 'M', 'm', 'B', 'b', 'H', 'h', 'u', or others) on tainted strings
You are affected if your Ruby version is 2.3.0-2.3.7, 2.4.0-2.4.4, 2.5.0-2.5.1, or 2.6.0 AND your code uses Array#pack or String#unpack on tainted data with format specifiers that fail to propagate the taint flag.
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 Ruby to version 2.3.8, 2.4.5, 2.5.2, or 2.6.0-preview3 or later to resolve the taint propagation issue.
Fix this in Ruby
Scoped from the published advisory
- Consultation4.0 h
- Implementation2.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,928.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-16396 — 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-2018-16396 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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