auth/ldap/ntlmsso_attempt.php in Moodle 2.0.x before 2.0.10, 2.1.x before 2.1.7, 2.2.x before 2.2.4, and 2.3.x before 2.3.1 redirects users from an https LDAP login URL to an http URL, which allows remote attackers to obtain sensitive information by sniffing the network.