Design/Logic Flaw

The wp-courses plugin through 2.0.27 for WordPress allows remote attackers to bypass the intended payment step (for course videos and materials) by using the /wp-json REST API, as exploited in the wild in September 2020. This occurs because show_in_rest is enabled for custom post types (e.g., /wp-json/wp/v2/course and /wp-json/wp/v2/lesson exist).