The ip_in_range function in mnet/lib.php in MNET in Moodle 1.9.x before 1.9.15 uses an incorrect data type, which allows remote attackers to bypass intended IP address restrictions via an XMLRPC request.
https://bugzilla.redhat.com/show_bug.cgi?id=761248
http://www.debian.org/security/2012/dsa-2421
http://moodle.org/mod/forum/discuss.php?d=191756
http://git.moodle.org/gw?p=moodle.git%3Ba=commit%3Bh=3ab2851d2a59721445945d0706c58092e07e861e