The Masteriyo LMS WordPress plugin before 3.4.2 does not verify that the user making the request...

The Masteriyo LMS WordPress plugin before 3.4.2 does not verify that the user making the request owns the course-progress records being returned, allowing any authenticated user, such as a self-registered subscriber, to read another user's learning activity. The ownership check it applies is skipped whenever the requested account is not named with a non-zero value, in which case the records of every learner on the site are returned at once.