LearnPress <= 4.3.6 - Unauthenticated Sensitive Information Exposure via 'c_status' and 'return_type' Parameters

The LearnPress – WordPress LMS Plugin for Create and Sell Online Courses plugin for WordPress is vulnerable to Sensitive Information Exposure in all versions up to, and including, 4.3.6 via the 'return_type' parameter. This makes it possible for unauthenticated attackers to extract sensitive data including the plaintext post_password of password-protected courses and the full post_content, post_author, and post_name of unpublished draft, private, and pending courses via the unrestricted SELECT * fallback query. Exploitation requires supplying both c_status=all (to bypass the publish-only post_status WHERE clause) and return_type=json (to prevent the safe DISTINCT(ID) AS ID field override) in a single unauthenticated request to the /wp-json/lp/v1/courses/archive-course endpoint.