Moodle through 2.3.11, 2.4.x before 2.4.11, 2.5.x before 2.5.7, 2.6.x before 2.6.4, and 2.7.x before 2.7.1 allows remote authenticated users to execute arbitrary code via a calculated question in a quiz.
https://moodle.org/mod/forum/discuss.php?d=264266
http://openwall.com/lists/oss-security/2014/07/21/1
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-46148