Debian Security Advisory DSA 157-1: Serious irssi DoS Risk Notification

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.

wget url
will fetch the file for you
dpkg -i file.deb
will install the referenced file.

If you are using the apt-get package manager, use the line for
sources.list as given below:

apt-get update
will update the internal database
apt-get upgrade
will install corrected packages

You may use an automated update by adding the resources...