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.

Bugs

• <https://bugs.launchpad.net/ubuntu/+source/fail2ban/+bug/181722&gt;