Moodle 2.0.x before 2.0.3 allows remote authenticated users to cause a denial of service (invalid database records) via a series of crafted comments operations.
http://openwall.com/lists/oss-security/2011/11/14/1
http://moodle.org/mod/forum/discuss.php?d=175594
http://git.moodle.org/gw?p=moodle.git%3Ba=commit%3Bh=acb4688d29a7cc028803ee3d81edc7f1b6515c64