Moodle 2.3.x before 2.3.1 uses only a client-side check for whether references are permitted in a file upload, which allows remote authenticated users to bypass intended alias (aka shortcut) restrictions via a client that omits this check.
https://exchange.xforce.ibmcloud.com/vulnerabilities/76954
http://www.securityfocus.com/bid/54481
http://secunia.com/advisories/49890
http://openwall.com/lists/oss-security/2012/07/17/1
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-33948