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