CentOS Errata and Security Advisory 2006:0052
https://rhn.redhat.com/errata/RHSA-2006-0052.html
The following updated files have been uploaded and are currently syncing to the mirrors:
x86_64: squid-2.5.STABLE6-3.4E.12.x86_64.rpm
src: squid-2.5.STABLE6-3.4E.12.src.rpm