filter.d/wuftpd.conf in Fail2ban 0.8.3 uses an incorrect regular expression that allows remote attackers to cause a denial of service (forced authentication failures) via a crafted reverse-resolved DNS name (rhost) entry that contains a substring that is interpreted as an IP address, a different vulnerability than CVE-2007-4321.

fail2ban 0.8 and earlier does not properly parse sshd log files, which allows remote attackers to add arbitrary hosts to the /etc/hosts.deny file and cause a denial of service by adding arbitrary IP addresses to the sshd log file, as demonstrated by logging in via ssh with a client protocol version identification containing an IP address string, a different vector than CVE-2006-6302.