Claude

bundler-audit — Security Auditing for Ruby Gems

What is bundler-audit?

bundler-audit is a tool that checks a project's Gemfile.lock against a database of known vulnerabilities (CVEs and GHSAs), identifying gems with security issues and recommending safe versions.

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Step-by-Step Installation

1. Add it to the Gemfile

Add it only to the development group — it is not required in production:

group :development do
  gem 'bundler-audit', require: false
end

2. Install project gems

bundle install

3. Update the vulnerability database

bundler-audit maintains a local copy of the advisory database. Always update it before auditing:

bundle exec bundler-audit update

The database contains hundreds of advisories (e.g., 1007 advisories, updated on 2025-08-15).

4. Run the audit

bundle exec bundler-audit check --update

The --update flag ensures the database is automatically updated before the scan.

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Interpreting Results

bundler-audit reports each vulnerable gem with:

Field	Description
Gem	Name of the affected gem
Version	Currently installed version
Advisory	CVE or GHSA identifier
Criticality	Severity level: Unknown / Low / Medium / High / Critical
Title	Short vulnerability description
Solution	Recommended safe version

Clean result:

No vulnerabilities found

Vulnerability found (example):

Name: rack
Version: 3.1.8
Advisory: CVE-2025-27610
Criticality: High
Title: Path traversal vulnerability
Solution: upgrade to >= 3.1.16

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Safe Update Strategy

Development / Staging Environment

You can update all vulnerable gems at once:

bundle update nokogiri rack net-imap activerecord activestorage rack-session thor uri

Production Environment (Recommended: Gradual Updates)

⚠️ Warning: In production, update one gem at a time and run tests after each update.

# 1. Update a single gem
bundle update rack

# 2. Run application tests
rails test -v

# 3. Verify bundler-audit is satisfied with the updated gem
bundle exec bundler-audit check

# 4. Repeat for the next gem

Update All System Gems (Optional)

gem update

Use with caution — this may introduce compatibility issues in projects that do not explicitly manage gem versions.

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Common Vulnerabilities (Reference)

Gem	Common CVEs	Risk Type
nokogiri	GHSA-mrxw-mxhj-p664	libxml2/libxslt issues
rack	CVE-2025-25184, 27610	Log injection, LFI, DoS, ReDoS
net-imap	CVE-2025-25186	Memory exhaustion DoS
activerecord	CVE-2025-55193	ANSI escape injection in logs
activestorage	CVE-2025-24293	Potentially unsafe transformations
rack-session	CVE-2025-46336	Session restoration after deletion
thor	CVE-2025-54314	Shell input injection
uri	CVE-2025-27221	Userinfo leakage in URI join/merge

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CI/CD Integration

Add the audit to your pipeline to block deployments when vulnerabilities are detected:

# GitHub Actions example
- name: Audit gems
  run: bundle exec bundler-audit check --update

The command returns exit code 1 if vulnerabilities are found, automatically stopping the pipeline.

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Recommended Complete Workflow

1. bundle exec bundler-audit update      # Update advisory database
2. bundle exec bundler-audit check       # Check for vulnerabilities
3. bundle update <vulnerable-gem>        # Update one gem at a time (production)
4. rails test -v                         # Verify nothing broke
5. bundle exec bundler-audit check       # Confirm the vulnerability is fixed
6. Repeat until: "No vulnerabilities found"

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What Are CVEs and GHSAs?

• CVE (Common Vulnerabilities and Exposures): a global vulnerability identifier maintained by MITRE. Example: CVE-2025-27610.
• GHSA (GitHub Security Advisory): a vulnerability identifier reported through GitHub. Example: GHSA-mrxw-mxhj-p664.
• Both are tracked by the bundler-audit advisory database.