The remote host is missing an update to XChat announced via advisory DSA 099-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20099-1

zen-parse found a vulnerability in the XChat IRC client that allows an attacker to take over the users IRC session. It is possible to trick XChat IRC clients into sending arbitrary commands to the IRC server they are on, potentially allowing social engineering attacks, channel takeovers, and denial of service. This problem exists in versions 1.4.2 and 1.4.3. Later versions of XChat are vulnerable as well, but this behaviour is controlled by the configuration variable »percascii«, which defaults to 0. If it is set to 1 then the problem becomes apparent in 1.6/1.8 a swell. This problem has been fixed in upstream version 1.8.7 and in version 1.4.3-1 for the current stable Debian release (2.2) with a patch provided from the upstream author Peter Zelezny. We recommend that you upgrade your XChat packages immediately, since this problem is already actively being exploited.