The remote host is vulnerable to an arbitrary 'command insertion' flaw.
The remote host is running AWStats, a CGI log analyzer. There are various content-parsing flaws in the remote version of this software that would allow an attacker to execute code on the remote host. An attacker exploiting this flaw would only need to be able to generate HTTP requests to the awstats.pl CGI script. A successful attack would allow the attacker to run system commands with the privileges of the CGI script.
Upgrade to AWStats 6.5 or higher.