The Masteriyo LMS WordPress plugin before 3.4.0 does not sanitise and escape some course settings before outputting them in a page available to all visitors, allowing users with a course-author role to perform Stored Cross-Site Scripting attacks that run in the session of anyone viewing the course, including a logged-in administrator.

The Masteriyo LMS WordPress plugin before 2.3.3 does not sanitise and escape a quiz field before outputting it back in a page, and grants its instructor role the ability to store unfiltered HTML, allowing such users to perform Stored Cross-Site Scripting attacks against any visitor of the affected page, including administrators. This affects default single-site installations. Sites running multisite, or defining DISALLOWUNFILTEREDHTML, are not affected as the capability is not granted there.