Moodle Exposure of Sensitive Information to an Unauthorized Actor Vulnerability - CVE-2016-2156
calendar/externallib.php in Moodle through 2.6.11 2.7.x before 2.7.13 2.8.x before 2.8.11 2.9.x before 2.9.5 and 3.0.x before 3.0.3 provides calendar-event data without considering whether an activity is hidden which allows remote authenticated users to obtain sensitive information via a web-service request.