The remote host is vulnerable to an flaw which allows attackers to execute arbitrary commands.
The remote host is running the XChat IRC client. X-Chat versions 1.8.8 and earlier could allow a remote attacker to execute arbitrary commands on the X-Chat client. A vulnerability regarding the lack of filtering in the EXECL command could allow an attacker to send a specially crafted /dns query that would return a malformed response from the server to execute arbitrary commands on the X-Chat client.
Upgrade or patch according to vendor recommendations.