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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 28 Jul 2025.
RailsApplication · Rubyonrails

CVE-2019-5418

HIGH · 7.5 CVSS v3.1 Published 2019-03-27
Fix available
A fix is available. Upgrade to 4.2.11.1 / 5.0.7.2 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild High EPSS Public exploit Remotely reachable No privileges Zero-click Patch available

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
There is a File Content Disclosure vulnerability in Action View <5.2.2.1, <5.1.6.2, <5.0.7.2, <4.2.11.1 and v3 where specially crafted accept headers can cause contents of arbitrary files on the target system's filesystem to be exposed.

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 confidence

A file content disclosure vulnerability in Action View (Ruby on Rails) where specially crafted HTTP Accept headers allow attackers to read arbitrary files from the server's filesystem via path traversal.

MitigationUpgrade Action View to patched versions (5.2.2.1+, 5.1.6.2+, 5.0.7.2+, 4.2.11.1+) or apply the corresponding Rails security patches.

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
RailsApplication
Affected:>= 3.0.0, < 4.2.11.1>= 5.0.0, < 5.0.7.2>= 5.1.0, < 5.1.6.2>= 5.2.0, < 5.2.2.1
Debian LinuxOperating system
Affected:= 8.0
CloudformsApplication
Affected:= 4.7= 4.6
FedoraOperating system
Affected:= 30
Software CollectionsApplication
Affected:= 1.0
LeapOperating system
Affected:= 15.0

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
High
Integrity
None
Availability
None

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

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

  1. Check installed Rails version
    Run 'rails -v' in your application directory, or inspect the Gemfile.lock for the Rails gem version, or run 'gem list rails'
    Affected if The Rails version is 3.0.0 through 4.2.11.0, 5.0.0 through 5.0.7.1, 5.1.0 through 5.1.6.1, or 5.2.0 through 5.2.2.0 (these ranges are vulnerable)
  2. Check Action View gem version
    Run 'gem list actionview' or inspect Gemfile.lock for the actionview gem version
    Affected if The actionview gem version is lower than 4.2.11.1, 5.0.7.2, 5.1.6.2, or 5.2.2.1 (these versions are vulnerable)
  3. Identify if Action View is in use
    Check if the application uses Rails and has Action View as a dependency (look for 'actionview' in Gemfile or Gemfile.lock)
    Affected if The application uses Rails with Action View as a dependency (which is default for Rails applications)
  4. Check for web-facing Rails application
    Identify if the Rails application has any web routes configured (check config/routes.rb) or is exposed via a web server (Apache, Nginx, Puma, Unicorn, etc.)
    Affected if The Rails application is web-facing and processes HTTP requests (the vulnerability is exploitable via HTTP Accept headers)

You are affected if your Rails version falls within the vulnerable ranges and your application processes HTTP requests using Action View, as the flaw allows arbitrary file read via crafted Accept headers.

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.

dbcve · scoped
Upgrade available Upgrade to 4.2.11.1 / 5.0.7.2 / 5.1.6.2 or later
Fixed in 4.2.11.15.0.7.25.1.6.2
Vendor patch www.openwall.com →
Interim mitigation

Upgrade Action View to patched versions (5.2.2.1+, 5.1.6.2+, 5.0.7.2+, 4.2.11.1+) or apply the corresponding Rails security patches.

Recommended fix High confidence

Rails 4.2.11.1, 5.0.7.2, 5.1.6.2, or 5.2.2.1 (choose based on current major/minor version)

  1. Identify the current Rails version by checking the Gemfile or running `rails -v`
  2. Determine the appropriate upgrade path based on current version (see upgrade_path)
  3. Update the Rails version in the Gemfile to the fixed version
  4. Run `bundle update rails` to update dependencies
  5. Verify the application works correctly with `rails server`
  6. Test that the file content disclosure vulnerability is no longer present by attempting a crafted Accept header request
Caveat Patch/minor upgrades within the same major.minor branch (e.g., 5.2.0 to 5.2.2.1) typically have minimal breaking changes; however, always review the changelog for the specific versions being upgraded

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Rails Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing4.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,900
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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-2019-5418 in production — separate from our analysis above.

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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