Tutor LMS <= 3.9.7 - Missing Authorization to Authenticated (Subscriber+) Unauthorized Private Course Enrollment

Summary

The Tutor LMS – eLearning and online course solution plugin for WordPress is vulnerable to unauthorized private course enrollment in all versions up to, and including, 3.9.7. This is due to missing post_status validation in the `enroll_now()` and `course_enrollment()` functions. Both enrollment endpoints verify the nonce, user authentication, and whether the course is purchasable, but fail to check if the course has a `private` post_status. This makes it possible for authenticated attackers with Subscriber-level access or above to enroll in private courses by sending a crafted POST request with the target course ID. The enrollment record is created in the database and the private course title and enrollment status are exposed in the subscriber's dashboard, though WordPress core access control prevents the subscriber from viewing the actual course content (returns 404). Enrollment in private courses should be restricted to users with the `read_private_posts` capability.