Tutor LMS < 4.0.0 - Subscriber+ Cross-Course Q&A Content Disclosure and Reply Injection

The Tutor LMS WordPress plugin before 4.0.0 does not properly verify that a user has access to the course a Q&A thread belongs to before returning or writing to that thread, allowing authenticated users with subscriber-level access and above who can access any single course to read the Q&A threads of other courses and to inject replies into them.