Multiple unspecified authentication plugins in Moodle 1.8 before 1.8.11 and 1.9 before 1.9.7 store the MD5 hashes for passwords in the user table, even when the cached hashes are not used by the plugin, which might make it easier for attackers to obtain credentials via unspecified vectors.
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=139105