Tutor LMS < 3.9.9 - Authenticated (Subscriber+) Arbitrary Course Content Manipulation via tutor_update_course_content_order

Description

The Tutor LMS – eLearning and online course solution plugin for WordPress is vulnerable to unauthorized course content manipulation in versions up to and including 3.9.8. This is due to a missing authorization check in the tutor_update_course_content_order() function. The function only validates the nonce (CSRF protection) but does not verify whether the user has permission to manage course content. The can_user_manage() authorization check only executes when the 'content_parent' parameter is present in the request. When this parameter is omitted, the function proceeds directly to save_course_content_order() which manipulates the wp_posts table without any authorization validation. This makes it possible for authenticated attackers with subscriber-level access and above to detach all lessons from any topic, move lessons between topics, and modify the menu_order of course content, effectively allowing them to disrupt the structure of any course on the site.