RubyApplication · Ruby Lang
CVE-2008-1891
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 · uneditedDirectory traversal vulnerability in WEBrick in Ruby 1.8.4 and earlier, 1.8.5 before 1.8.5-p231, 1.8.6 before 1.8.6-p230, 1.8.7 before 1.8.7-p22, and 1.9.0 before 1.9.0-2, when using NTFS or FAT filesystems, allows remote attackers to read arbitrary CGI files via a trailing (1) + (plus), (2) %2b (encoded plus), (3) . (dot), (4) %2e (encoded dot), or (5) %20 (encoded space) character in the URI, possibly related to the WEBrick::HTTPServlet::FileHandler and WEBrick::HTTPServer.new functionality and the :DocumentRoot option.
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 confidenceDirectory traversal vulnerability in WEBrick (Ruby's HTTP server) allows remote attackers to read arbitrary CGI files via specially crafted URIs containing trailing characters (+, %2b, ., %2e, or %20) when the server runs on NTFS or FAT filesystems. The flaw exists in WEBrick::HTTPServlet::FileHandler when handling the :DocumentRoot option.
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
<= 1.9.0= 1.8.5= 1.8.6CVSS 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
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- None
- Availability
- None
AV:N/AC:L/Au:N/C:P/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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Identify Ruby versionRun 'ruby --version' to obtain the installed Ruby interpreter versionAffected if Version is 1.8.5, 1.8.6, or any 1.9.0 or earlier
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Confirm WEBrick is in useSearch codebase or running processes for WEBrick::HTTPServlet::FileHandler or require 'webrick' statementsAffected if WEBrick is being used as the HTTP server
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Check DocumentRoot configurationInspect WEBrick configuration for :DocumentRoot option - look for WEBrick::Config::FileHandler or HTTPServlet::FileHandler.new setupAffected if :DocumentRoot points to a directory path on the server
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Verify filesystem type of DocumentRootDetermine the filesystem type where :DocumentRoot directory resides - on Windows use 'fsutil fsinfo volumeinfo <drive>' or check if Windows with NTFS/FAT; on Linux check if mounted on NTFS/FAT partitionAffected if DocumentRoot is on an NTFS or FAT filesystem (vulnerable only on these)
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Test for path traversal with special charactersSend HTTP requests with URIs containing '../' followed by trailing characters (+, %2b, ., %2e, or %20) to access files outside DocumentRoot (e.g., /..%2f/../../etc/passwd)Affected if Server returns content from files outside the intended DocumentRoot directory
A system is affected if it runs a vulnerable Ruby version (1.8.5, 1.8.6, or <=1.9.0), uses WEBrick with a :DocumentRoot on an NTFS or FAT filesystem, and serves CGI files to remote users.
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 to a patched Ruby version (1.8.5-p231+, 1.8.6-p230+, 1.8.7-p22+, or 1.9.0-2+) or ensure WEBrick is not used in production with untrusted document roots on NTFS/FAT filesystems.
Fix this in Ruby
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,128.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2008-1891 — 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-2008-1891 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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