login/index_form.html in Moodle 1.8 before 1.8.11 and 1.9 before 1.9.7 links to an index page on the HTTP port even when the page is served from an HTTPS port, which might cause login credentials to be sent in cleartext, even when SSL is intended, and allows remote attackers to obtain these credentials by sniffing.
https://www.redhat.com/archives/fedora-package-announce/2009-December/msg00751.html
https://www.redhat.com/archives/fedora-package-announce/2009-December/msg00730.html
https://www.redhat.com/archives/fedora-package-announce/2009-December/msg00704.html
http://www.vupen.com/english/advisories/2009/3455
http://www.securityfocus.com/bid/37244
http://secunia.com/advisories/37614
http://moodle.org/mod/forum/discuss.php?d=139107