Cross-site scripting (XSS) vulnerability in group/overview.php in Moodle through 2.6.11, 2.7.x before 2.7.10, 2.8.x before 2.8.8, and 2.9.x before 2.9.2 allows remote authenticated users to inject arbitrary web script or HTML via a modified grouping description.
https://moodle.org/mod/forum/discuss.php?d=320293
http://www.securitytracker.com/id/1033619
http://www.openwall.com/lists/oss-security/2015/09/21/1
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-50709