A flaw was found in the coreos-installer, where it writes the Ignition config to the target system with world-readable access permissions. This flaw allows a local attacker to have read access to potentially sensitive data. The highest threat from this vulnerability is to confidentiality.
https://github.com/coreos/fedora-coreos-tracker/issues/889
https://github.com/coreos/coreos-installer/commit/2a36405339c87b16ed6c76e91ad5b76638fbdb0c