Implementations of SSH version 1.5, including (1) OpenSSH up to version 2.3.0, (2) AppGate, and (3) ssh-1 up to version 1.2.31, in certain configurations, allow a remote attacker to decrypt and/or alter traffic via a "Bleichenbacher attack" on PKCS#1 version 1.5.
https://exchange.xforce.ibmcloud.com/vulnerabilities/6082
http://www.securityfocus.com/bid/2344
http://www.novell.com/linux/security/advisories/adv004_ssh.html
http://www.debian.org/security/2001/dsa-086
http://www.debian.org/security/2001/dsa-027
http://www.debian.org/security/2001/dsa-023