access.php in the Lesson module in Moodle 2.8.x before 2.8.2 does not set the RISK_XSS bit for graders, which allows remote authenticated users to conduct cross-site scripting (XSS) attacks via crafted essay feedback.
https://moodle.org/mod/forum/discuss.php?d=278616
http://openwall.com/lists/oss-security/2015/01/19/1
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-48034