OpenSSH 4.0, and other versions before 4.2, does not properly handle dynamic port forwarding ("-D" option) when a listen address is not provided, which may cause OpenSSH to enable the GatewayPorts functionality.
http://www.securityfocus.com/bid/14727
http://www.mindrot.org/pipermail/openssh-unix-announce/2005-September/000083.html
http://support.avaya.com/elmodocs2/security/ASA-2006-033.htm
http://securitytracker.com/id?1014845
http://secunia.com/advisories/19243
http://secunia.com/advisories/18661
http://secunia.com/advisories/18010