Overview
CVE-2026-31233 describes a code injection vulnerability in Guardrails AI up to version 0.6.7, specifically in its Hub package installation mechanism. When a user runs guardrails hub install to install validator packages, the Hub fetches a manifest and dynamically executes the script specified in the post_install field. The script path is derived from untrusted manifest data and is executed without sufficient validation or sanitization, enabling remote code execution if a malicious package is published to the Hub. This demonstrates how an attacker who can publish malicious packages can cause arbitrary code execution on any system that installs those packages. While the CVE concerns Guardrails Hub, the same fundamental flaw-executing untrusted, externally supplied scripts or code-poses a risk for Ruby on Rails applications that adopt similar patterns in plugin, gem, or extension installation workflows. The real-world impact includes remote code execution, potential system compromise, data exfiltration, and lateral movement within a host or container environment. The vulnerability highlights CWE-94 (Code Injection) by showing how untrusted manifest data can drive the execution of attacker-controlled code during installation processes.
Affected Versions
Guardrails Hub <= 0.6.7 (CVE-2026-31233)
Code Fix Example
Ruby on Rails API Security Remediation
Vulnerable pattern (illustrative, not Rails-specific):
```ruby
require 'json'
require 'net/http'
# Vulnerable: fetches a manifest and executes a post_install script path derived from manifest data
def install_package(manifest_url)
manifest = Net::HTTP.get(URI(manifest_url))
data = JSON.parse(manifest)
script_path = File.join('/tmp', data['post_install'])
system(script_path) # untrusted external code executed
end
# Usage
# install_package('https://example.com/manifest.json')
```
Safe, Rails-aware fix (avoid executing untrusted external scripts; map to whitelisted internal tasks):
```ruby
require 'json'
require 'net/http'
# Define a whitelist of safe installation tasks that are implemented in code
WHITELISTED_TASKS = {
'install_assets' => -> { Rails.logger.info('Precompiling assets'); system('bundle exec rake assets:precompile') },
'verify_database' => -> { Rails.logger.info('Running migrations'); system('bundle exec rake db:migrate') }
}.freeze
def install_package_secure(manifest_url)
manifest_json = Net::HTTP.get(URI(manifest_url))
manifest = JSON.parse(manifest_json)
post_install = manifest['post_install']
task = WHITELISTED_TASKS[post_install]
raise "Unsupported post_install task: #{post_install}" unless task
# Execute only whitelisted internal tasks, never external scripts
task.call
end
# Usage
# install_package_secure('https://example.com/manifest.json')
```