Moby is an open source container framework developed by Docker Inc. that is distributed as Docker Engine, Mirantis Container Runtime, and various other downstream projects/products. In versions 28.2.0 through 28.3.2, when the firewalld service is reloaded it removes all iptables rules including those created by Docker. While Docker should automatically recreate these rules, versions before 28.3.3 fail to recreate the specific rules that block external access to containers.

This means that after a firewalld reload, containers with ports published to localhost (like 127.0.0.1:8080) become accessible from remote machines that have network routing to the Docker bridge, even though they should only be accessible from the host itself. The vulnerability only affects explicitly published ports - unpublished ports remain protected. This issue is fixed in version 28.3.3.