New Security Errata for Centos-3 x86 Systems:
This affects all releases of Centos-3:

libtiff: https://rhn.redhat.com/errata/RHSA-2005-019.html
RPMS/libtiff-3.5.7-22.el3.i386.rpm
RPMS/libtiff-devel-3.5.7-22.el3.i386.rpm
SRPMS/libtiff-3.5.7-22.el3.src.rpm

mozilla: https://rhn.redhat.com/errata/RHSA-2005-038.html
RPMS/mozilla-1.4.3-3.0.7.centos.1.i386.rpm
RPMS/mozilla-chat-1.4.3-3.0.7.centos.1.i386.rpm
RPMS/mozilla-devel-1.4.3-3.0.7.centos.1.i386.rpm
RPMS/mozilla-dom-inspector-1.4.3-3.0.7.centos.1.i386.rpm
RPMS/mozilla-js-debugger-1.4.3-3.0.7.centos.1.i386.rpm
RPMS/mozilla-mail-1.4.3-3.0.7.centos.1.i386.rpm
RPMS/mozilla-nspr-1.4.3-3.0.7.centos.1.i386.rpm
RPMS/mozilla-nspr-devel-1.4.3-3.0.7.centos.1.i386.rpm
RPMS/mozilla-nss-1.4.3-3.0.7.centos.1.i386.rpm
RPMS/mozilla-nss-devel-1.4.3-3.0.7.centos.1.i386.rpm
SRPMS/mozilla-1.4.3-3.0.7.centos.1.src.rpm

To Apply these updates run:
yum update