CVE 2014-7845
The generate_password function in Moodle through 2.4.11, 2.5.x before 2.5.9, 2.6.x before 2.6.6, and 2.7.x before 2.7.3 does not provide a sufficient number of possible temporary passwords, which allows remote attackers to obtain access via a brute-force attack.
See the 
CVE page on Mitre.org
for more details.
