The image build process for the overcloud images in Red Hat OpenStack Platform 8.0 (Liberty) director and Red Hat Enterprise Linux OpenStack Platform 7.0 (Kilo) director (aka overcloud-full) use a default root password of ROOTPW, which allows attackers to gain access via unspecified vectors.
https://rhn.redhat.com/errata/RHSA-2016-1223.html