fail2ban 0.7.4 and earlier does not properly parse sshd log files, which allows remote attackers to add arbitrary hosts to the /etc/hosts.d…

fail2ban 0.7.4 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 login name containing certain strings with an IP address.