Buffer overflow in Webalizer 2.01-06, when configured to use reverse DNS lookups, allows remote attackers to execute arbitrary code by connecting to the monitored web server from an IP address that resolves to a long hostname.
https://exchange.xforce.ibmcloud.com/vulnerabilities/8837
http://www.securityfocus.com/bid/4504
http://www.mrunix.net/webalizer/news.html