GitLab: Drive-by arbitrary file deletion in the GDK via letter_opener_web gem

Summary When running gitlab in development, an extra gem used to view emails that have been sent: https://gitlab.com/gitlab-org/gitlab/-/blob/v14.3.0-ee/config/routes/development.rbL14 ruby mount LetterOpenerWeb::Engine, at: '/rails/letteropener' One of the routes it adds is to delete a letter:...