The Quiz and Survey Master (QSM) WordPress plugin before 11.2.4 does not check authorisation when returning question bank entries through one of its REST API routes, allowing users with a role as low as Contributor to read the questions, hints and correct answer keys of quizzes belonging to other users.
https://wpscan.com/vulnerability/f4c77fda-edc2-44c5-95d9-358636896b5f/