OpenSSH SSH client before 2.3.0 does not properly disable X11 or agent forwarding, which could allow a malicious SSH server to gain access to the X11 display and sniff X11 events, or gain access to the ssh-agent.
https://exchange.xforce.ibmcloud.com/vulnerabilities/5517
http://www.securityfocus.com/bid/1949
http://www.redhat.com/support/errata/RHSA-2000-111.html
http://www.linux-mandrake.com/en/security/MDKSA-2000-068.php3
http://www.debian.org/security/2000/20001118
http://lists.suse.com/archives/suse-security-announce/2000-Nov/0004.html
http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000345
http://archives.neohapsis.com/archives/bugtraq/2000-11/0217.html
http://archives.neohapsis.com/archives/bugtraq/2000-11/0195.html