CentOS Errata and Security Advisory 2006:0204
https://rhn.redhat.com/errata/RHSA-2006-0204.html
The following updated files have been uploaded and are currently syncing to the mirrors:
i386: mailman-2.1.5.1-34.rhel4.2.i386.rpm
src: mailman-2.1.5.1-34.rhel4.2.src.rpm