backup/moodle2/restore_stepslib.php in Moodle 2.0.x before 2.0.6 and 2.1.x before 2.1.3 does not check for the moodle/course:changeidnumber privilege during handling of course ID numbers, which allows remote authenticated users to overwrite ID numbers via a restore action.
https://bugzilla.redhat.com/show_bug.cgi?id=761248
http://moodle.org/mod/forum/discuss.php?d=191758
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-29591