Insufficient web service capability checks made it possible to move categories a user had permission to manage, to a parent category they did not have the capability to manage.
https://moodle.org/mod/forum/discuss.php?d=451590
https://bugzilla.redhat.com/show_bug.cgi?id=2243451
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-66730