The remote host is missing an update to irssi-text announced via advisory DSA 157-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20157-1

The IRC client irssi is vulnerable to a denial of service condition. The problem occurs when a user attempts to join a channel that has an overly long topic description. When a certain string is appended to the topic, irssi will crash. This problem has been fixed in version 0.8.4-3.1 for the current stable stable distribution (woody) and in version 0.8.5-2 for the unstable distribution (sid). The old stable distribution (potato) is not affected, since the corresponding portions of code are not present. The same applies to irssi-gnome and irssi-gtk, which don't seem to be affected as well. We recommend that you upgrade your irssi-text package.