There are updated imlib packages for CentOS 3.3 (and added to 3.1)

https://rhn.redhat.com/errata/RHSA-2004-651.html refers

Updated files are :-

updates/i386/RPMS/imlib-1.9.13-13.4.i386.rpm
updates/i386/RPMS/imlib-cfgeditor-1.9.13-13.4.i386.rpm
updates/i386/RPMS/imlib-devel-1.9.13-13.4.i386.rpm

updates/i386/SRPMS/imlib-1.9.13-13.4.src.rpm


These are available at http://mirror.centos.org/centos/3.3/ and should be on all mirrors within a few hours

To update to the latest version 'yum update imlib' should be
sufficient.