Moby's Firewalld reload removes bridge network isolation

Vulnerability Description

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. A firewalld vulnerability affects Moby releases before 28.0.0. When firewalld reloads, Docker fails to re-create iptables rules that isolate bridge networks, allowing any container to access all ports on any other container across different bridge networks on the same host. This breaks network segmentation between containers that should be isolated, creating significant risk in multi-tenant environments. Only containers in --internal networks remain protected. Workarounds include reloading firewalld and either restarting the docker daemon, re-creating bridge networks, or using rootless mode. Maintainers anticipate a fix for this issue in version 25.0.13.

References

• https://github.com/moby/moby/security/advisories/GHSA-4vq8-7jfc-9cvp
• https://firewalld.org/documentation/howto/reload-firewalld.html