Clockwork Web before 0.1.2, when Rails before 5.2 is used, allows CSRF.
https://github.com/ankane/clockwork_web/issues/4
https://github.com/ankane/clockwork_web/compare/v0.1.1...v0.1.2
https://github.com/ankane/clockwork_web/commit/ec2896503ee231588547c2fad4cb93a94e78f857