The Masteriyo LMS – eLearning and Online Course Builder for WordPress plugin for WordPress is vulnerable to unauthorized user profile modification due to missing authorization checks on the /wp-json/masteriyo/v1/users/$id REST API endpoint in all versions up to, and including, 1.13.3. This makes it possible for authenticated attackers, with student-level access and above, to modify the roles of arbitrary users. As a result, attackers can escalate their privileges to the Administrator and demote existing administrators to students.