The MoodleQuickForm class in the Forms Library in lib/formslib.php in Moodle 1.9.x before 1.9.14, 2.0.x before 2.0.5, and 2.1.x before 2.1.2 does not recognize Forms API setConstant operations, which allows remote attackers to submit unexpected form content by modifying the values of constant fields.
https://bugzilla.redhat.com/show_bug.cgi?id=747444
http://moodle.org/mod/forum/discuss.php?d=188313
http://git.moodle.org/gw?p=moodle.git%3Ba=commit%3Bh=f1f70bd4dde6cd1ea4bdb8ab28fa3d36a53b89d8