Kramdown before 2.3.1 does not restrict Rouge formatters to the Rouge::Formatters namespace, and thus arbitrary classes can be instantiated.
{ "nvd_published_at": "2021-03-19T07:15:00Z", "cwe_ids": [ "CWE-94" ], "severity": "HIGH", "github_reviewed": true, "github_reviewed_at": "2021-03-22T20:16:56Z" }