webservice/lib.php in Moodle 2.1.x before 2.1.8, 2.2.x before 2.2.5, and 2.3.x before 2.3.2 does not properly restrict the use of web-service tokens, which allows remote authenticated users to run arbitrary external-service functions via a token intended for only one service.
http://openwall.com/lists/oss-security/2012/09/17/1
http://moodle.org/mod/forum/discuss.php?d=211559
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-34368