Rails remote code execution using render :inline
Description
Ruby on Rails applications using the render method with the :inline option are vulnerable to remote code execution when user-controlled input is passed directly to this method without proper validation. This vulnerability affects Rails controllers and views that dynamically render inline templates based on untrusted data, allowing attackers to inject and execute arbitrary Ruby code on the server.
Remediation
Take immediate action to remediate this vulnerability using one of the following approaches:
1. Upgrade Ruby on Rails (Recommended)
Update to a patched version: Rails 4.2.5.2, 4.1.14.2, 3.2.22.2, or later.
2. Remove Inline Rendering with User Input
Avoid passing user-controlled data to the render method. Instead of:
render inline: params[:template] # VULNERABLE
Use predefined templates with a whitelist approach:
allowed_templates = ['template1', 'template2', 'template3'] template_name = allowed_templates.include?(params[:template]) ? params[:template] : 'default' render template_name
3. Validate and Sanitize Input
If dynamic rendering is absolutely necessary, implement strict input validation using a whitelist of allowed values. Never trust user input directly.
Consult the referenced security advisories for additional details and upgrade instructions specific to your Rails version.