Overview
Ruby on Rails CVE-2006-4111 (CWE-94) describes an Improper Inventory Management style vulnerability in Rails prior to 1.1.5 where remote attackers could cause arbitrary Ruby code execution via a File Upload request that includes an HTTP header designed to modify the LOAD_PATH. This class of vulnerability emerges when an application trusts request inputs to influence runtime loading or evaluation, effectively allowing an attacker to inject and run code with the app's privileges. The patch provided with Rails 1.1.5 and later fixed this by disallowing client-controlled changes to the load path and by removing unsafe patterns that execute uploaded content as code. Upgrading to a patched Rails version and eliminating dynamic code execution paths are essential protections in modern Ruby on Rails apps.
Affected Versions
Rails < 1.1.5
Code Fix Example
Ruby on Rails API Security Remediation
Vulnerable pattern (demonstrative, not for production use):
class UploadsController < ApplicationController
def create
uploaded = params[:file]
# Attacker-controlled header influences LOAD_PATH
if (lp = request.headers['X-Load-Path'])
$LOAD_PATH.unshift(lp)
end
# Dangerous: executes uploaded content as Ruby code
code = uploaded.read
eval(code)
end
end
Fixed pattern (safer approach):
class UploadsController < ApplicationController
def create
uploaded = params[:file]
# Do NOT modify LOAD_PATH from user input
content = uploaded.read
# Do NOT eval or load user-provided code
dest = Rails.root.join('tmp', 'uploads', SecureRandom.uuid + File.extname(uploaded.original_filename))
File.open(dest, 'wb') { |f| f.write(content) }
Rails.logger.info "Stored uploaded file to #{dest}"
end
end