Moodle 1.9.x before 1.9.16, 2.0.x before 2.0.7, 2.1.x before 2.1.4, and 2.2.x before 2.2.1 does not validate e-mail address settings, which allows remote authenticated users to have an unspecified impact via a crafted address.
https://bugzilla.redhat.com/show_bug.cgi?id=783532
http://www.debian.org/security/2012/dsa-2421
http://moodle.org/mod/forum/discuss.php?d=194014
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-13572