I have Debian Squeeze installed on my one of my workstation. On my Ubuntu 10.04 workstation there have been two security updates to the libtiff4 package in the last couple of weeks, addressing the CVE-2012-2088 vulnerability, but none to libtiff4 on the Debian installation.
Is the libtiff4 package installed on my Debian system [3.9.4-5+squeeze4] vulnerable? What update fixes it?
More generally, how can I find out whether and when a vulnerability is fixed in Debian?