CVE 2012-2357

The Multi-Authentication feature in the Central Authentication Service (CAS) functionality in auth/cas/cas_form.html in Moodle 2.1.x before 2.1.6 and 2.2.x before 2.2.3 does not use HTTPS, which allows remote attackers to obtain credentials by sniffing the network.

See the CVE page on Mitre.org for more details.