CVE 2012-3390
lib/filelib.php in Moodle 2.1.x before 2.1.7 and 2.2.x before 2.2.4 does not properly restrict file access after a block has been hidden, which allows remote authenticated users to obtain sensitive information by reading a file that is embedded in a block.
See the 
CVE page on Mitre.org
for more details.
