The following errata for CentOS-2 have been built and uploaded to the centos mirror:

RHSA-2006:0156-01 Moderate: ethereal security update

Files available:
ethereal-0.10.14-1.AS21.1.i386.rpm
ethereal-gnome-0.10.14-1.AS21.1.i386.rpm

More details are available from the RedHat web site at
https://rhn.redhat.com/errata/rh21as-errata.html

The easy way to make sure you are up to date with all the latest patches is to run:
# yum update