blockhosts.py in BlockHosts before 2.0.3 does not properly parse daemon log files, which allows remote attackers to add arbitrary deny entries to the /etc/hosts.allow file and cause a denial of service by adding arbitrary IP addresses to a daemon log file, as demonstrated by logging in through ssh using a login name containing certain strings with an IP address, which is not properly handled by a regular expression, a related issue to CVE-2006-6301.