lib/ajax/getnavbranch.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, when the forcelogin feature is enabled, allows remote attackers to obtain sensitive category-detail information from the navigation branch by leveraging the guest role for an Ajax request.
https://moodle.org/mod/forum/discuss.php?d=330180
http://www.securitytracker.com/id/1035333
http://www.openwall.com/lists/oss-security/2016/03/21/1
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-52774