lib/moodlelib.php in Moodle through 2.5.9, 2.6.x before 2.6.9, 2.7.x before 2.7.6, and 2.8.x before 2.8.4, when the theme uses the blocks-regions feature, establishes the course state at an incorrect point in the login-validation process, which allows remote attackers to obtain sensitive course information via unspecified vectors.
https://moodle.org/mod/forum/discuss.php?d=307384
http://openwall.com/lists/oss-security/2015/03/16/1
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-48804