Kramdown before 2.3.1 does not restrict Rouge formatters to the Rouge::Formatters namespace, and thus arbitrary classes can be instantiated.
{ "availability": "No subscription required", "binaries": [ { "binary_name": "kramdown", "binary_version": "1.17.0-4ubuntu0.2" }, { "binary_name": "ruby-kramdown", "binary_version": "1.17.0-4ubuntu0.2" } ] }
{ "availability": "No subscription required", "binaries": [ { "binary_name": "kramdown", "binary_version": "2.3.1-4" }, { "binary_name": "ruby-kramdown", "binary_version": "2.3.1-4" } ] }