CentOS Errata and Security Advisory 2006:0045
https://rhn.redhat.com/errata/RHSA-2006-0045.html
The following updated files have been uploaded and are currently syncing to the mirrors:
s390: updates/s390/RPMS/squid-2.5.STABLE3-6.3E.16.s390.rpm
s390x: updates/s390x/RPMS/squid-2.5.STABLE3-6.3E.16.s390x.rpm