An updated ncompress package is available for CentOS-2
The following errata for CentOS-2 have been built and uploaded the the centos mirror:
RHSA-2004:536-01 Updated ncompress package fixes security issue and bug
Files available:
ncompress-4.2.4-37.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