The vulnerability was found Moodle which exists due to insufficient limitations on the "start page" preference. A remote attacker can set that preference for another user. The vulnerability allows a remote attacker to gain unauthorized access to otherwise restricted functionality.
https://moodle.org/mod/forum/discuss.php?d=443274#p1782023
https://bugzilla.redhat.com/show_bug.cgi?id=2162549
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-76862