LearnDash LMS <= 5.0.3 - Authenticated (Contributor+) SQL Injection via 'filters[orderby_order]' Parameter

The LearnDash LMS plugin for WordPress is vulnerable to blind time-based SQL Injection via the 'filters[orderby_order]' parameter in the 'learndash_propanel_template' AJAX action in all versions up to, and including, 5.0.3. This is due to insufficient escaping on the user supplied parameter and lack of sufficient preparation on the existing SQL query. This makes it possible for authenticated attackers, with Contributor-level access and above, to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database.