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.
docs.moodle.org/en/Moodle_1.8.11_release_notes
docs.moodle.org/en/Moodle_1.9.7_release_notes
moodle.org/mod/forum/discuss.php?d=139107
secunia.com/advisories/37614
www.securityfocus.com/bid/37244
www.vupen.com/english/advisories/2009/3455
www.redhat.com/archives/fedora-package-announce/2009-December/msg00704.html
www.redhat.com/archives/fedora-package-announce/2009-December/msg00730.html
www.redhat.com/archives/fedora-package-announce/2009-December/msg00751.html