dbcve.org
RubyApplication · Ruby Lang

CVE-2019-15845

MEDIUM · 6.5 CVSS v3.1 Published 2019-11-26
Fix available
A fix is available. Upgrade to after 2.6.4 or later.
See remediation →
74/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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 · unedited
Ruby through 2.4.7, 2.5.x through 2.5.6, and 2.6.x through 2.6.4 mishandles path checking within File.fnmatch functions.

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 confidence

Ruby through 2.4.7, 2.5.x through 2.6.4 contains a path checking vulnerability in the File.fnmatch and File.fnmatch? functions. The functions mishandle certain path patterns, potentially allowing security controls to be bypassed when matching file paths against patterns.

MitigationUpgrade Ruby to version 2.4.8+, 2.5.7+, or 2.6.5+ respectively, or later stable releases. Review applications using File.fnmatch to ensure proper input validation is in place as a defense-in-depth measure.

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
Affected:>= 2.4.0, <= 2.4.7>= 2.5.0, <= 2.5.6>= 2.6.0, <= 2.6.4
Ubuntu LinuxOperating system
Affected:= 16.04= 18.04= 19.04= 19.10

CVSS 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
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Ruby version
    Run `ruby --version` or `ruby -v` from the command line to get the exact version number
    Affected if The version falls within 2.4.0-2.4.7, 2.5.0-2.5.6, or 2.6.0-2.6.4
  2. Check if File.fnmatch is used in application code
    Search source files for occurrences of `File.fnmatch` or `File.fnmatch?` using grep or a similar search tool across the codebase
    Affected if The application code contains calls to File.fnmatch or File.fnmatch? for path validation or pattern matching
  3. Review fnmatch pattern arguments for vulnerability triggers
    Examine the patterns passed to File.fnmatch to identify if they could be exploited with crafted path inputs (e.g., patterns that should not match escaped or specially crafted paths)
    Affected if The fnmatch patterns are used for security-critical path validation without additional input sanitization

You are affected if your installed Ruby version is 2.4.0-2.4.7, 2.5.0-2.5.6, or 2.6.0-2.6.4 and your application uses File.fnmatch or File.fnmatch? for path security checks.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Upgrade available Upgrade to a release after 2.6.4
Interim mitigation

Upgrade Ruby to version 2.4.8+, 2.5.7+, or 2.6.5+ respectively, or later stable releases. Review applications using File.fnmatch to ensure proper input validation is in place as a defense-in-depth measure.

Fix this in Ruby Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2019-15845 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-15845 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data