The Dropbox Repository File Picker in Moodle 2.1.x before 2.1.9, 2.2.x before 2.2.6, and 2.3.x before 2.3.3 allows remote authenticated users to access the Dropbox of a different user by leveraging an unattended workstation after a logout.
https://moodle.org/mod/forum/discuss.php?d=216155
http://www.securityfocus.com/bid/56505
http://openwall.com/lists/oss-security/2012/11/19/1
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-29872