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.
Category : Permissions, Privileges, and Access Controls Weaknesses in this category are related to the management of permissions, privileges, and other security features that are used to perform access control.