The SSH protocols 1 and 2 (aka SSH-2) as implemented in OpenSSH and other packages have various weaknesses which can allow a remote attacker to obtain the following information via sniffing: (1) password lengths or ranges of lengths, which simplifies brute force password guessing, (2) whether RSA or DSA authentication is being used, (3) the number of authorized_keys in RSA authentication, or (4) the lengths of shell commands.
http://www.redhat.com/support/errata/RHSA-2001-033.html
http://www.linux-mandrake.com/en/security/2001/MDKSA-2001-033.php3
http://www.kb.cert.org/vuls/id/596827
http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000391