The simple_captcha2 gem 0.2.3 for Ruby, as distributed on RubyGems.org, included a code-execution backdoor inserted by a third party.
{ "nvd_published_at": "2019-07-26T05:15:00Z", "cwe_ids": [ "CWE-94" ], "severity": "CRITICAL", "github_reviewed": true, "github_reviewed_at": "2019-07-31T04:00:04Z" }