activesupport vulnerable to Denial of Service via large XML document depth
The (1) `jdom.rb` and (2) `rexml.rb` components in Active Support in Ruby on Rails before 3.2.22, 4.1.x before 4.1.11, and 4.2.x before 4.2.2, when JDOM or REXML is enabled, allow remote attackers to cause a denial of service (SystemStackError) via a large XML document depth.