Debian: DSA 197-1 Critical: Courier Buffer Overflow Threat

A problem in the Courier sqwebmail package, a CGI program to grant
authenticated access to local mailboxes, has been discovered. The
program did not drop permissions fast enough upon startup under
certain circumstances so a local shell user can execute the sqwebmail
binary and manage to read an arbitrary file on the local filesystem.

This problem has been fixed in version 0.37.3-2.3 for the current
stable distribution (woody) and in version 0.40.0-1 for the unstable
distribution (sid). The old stable distribution (potato) does not
contain Courier sqwebmail packages.

We recommend that you upgrade your sqwebmail package immediately.

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 from the
foo...