Cross-site request forgery (CSRF) vulnerability in auth/shibboleth/logout.php in Moodle through 2.5.9, 2.6.x before 2.6.7, 2.7.x before 2.7.4, and 2.8.x before 2.8.2 allows remote attackers to hijack the authentication of arbitrary users for requests that trigger a logout.
https://moodle.org/mod/forum/discuss.php?d=278618
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-47964