Denial of Service (DoS) Affecting actionpack package, versions < 5.0.0.beta1, >= 4.3 < 4.2.5.1, >= 4.2 < 4.1.14.1, >= 4.0.0

actionpack is a web app builder and tester on Rails. Affected versions of this Gem are vulnerable to Denial of Service (DoS) attacks.

Ruby on Rails applications that have a route containing the string ":controller" are susceptible to denial of service caused by unbounded memory growth.

Action Pack keeps a map of url controller name to controller class name. This map is cached globally, and is populated even if the controller class doesn't actually exist. An attacker could flood a vulnerable application route with requests for non-existent controllers, leading to unbounded memory growth in this cache.

To identify if your application is vulnerable, look for routes that contain ":controller".

• http://rubysec.com/advisories/CVE-2015-7581
• https://groups.google.com/forum/#!topic/rubyonrails-security/dthJ5wL69JE