The (1) core_enrol_get_course_enrolment_methods and (2) enrol_self_get_instance_info web services in Moodle through 2.6.11, 2.7.x before 2.7.12, 2.8.x before 2.8.10, 2.9.x before 2.9.4, and 3.0.x before 3.0.2 do not consider the moodle/course:viewhiddencourses capability, which allows remote authenticated users to obtain sensitive information via a web-service request.