CentOS Errata and Security Advisory 2005:601
https://rhn.redhat.com/errata/RHSA-2005-601.html
The following updated files have been uploaded and are currently syncing to the mirrors:
i386: thunderbird-1.0.6-1.4.1.centos4.i386.rpm
src: thunderbird-1.0.6-1.4.1.centos4.src.rpm