AWStats 6.5, and possibly other versions, allows remote authenticated users to execute arbitrary code by using the configdir parameter to awstats.pl to upload a configuration file whose name contains shell metacharacters, then access that file using the LogFile directive.
http://www.vupen.com/english/advisories/2006/1998
http://www.securityfocus.com/bid/18327
http://www.osreviews.net/reviews/comm/awstats
http://www.novell.com/linux/security/advisories/2006_33_awstats.html
http://www.debian.org/security/2006/dsa-1075
http://secunia.com/advisories/20710
http://secunia.com/advisories/20502
http://secunia.com/advisories/20283