CVE 2013-2081
Moodle through 2.1.10, 2.2.x before 2.2.10, 2.3.x before 2.3.7, and 2.4.x before 2.4.4 does not consider "don't send" attributes during hub registration, which allows remote hubs to obtain sensitive site information by reading form data.
See the 
CVE page on Mitre.org
for more details.
