Moby firewalld reload makes published container ports accessible from remote hostsCVE-2025-54388

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. The Moby daemon component (dockerd), which is developed as [moby/moby](https://github.com/moby/moby) is commonly referred to as Docker, or Docker Engine. Firewalld is a daemon used by some Linux distributions to provide a dynamically managed firewall. When Firewalld is running, Docker uses its iptables backend to create rules, including rules to isolate containers in one bridge network from containers in other bridge networks. ### Impact The iptables rules created by Docker are removed when firewalld is reloaded using, for example "firewall-cmd --reload", "killall -HUP firewalld", or "systemctl reload firewalld". When that happens, Docker must re-create the rules. However, in affected versions of Docker, the iptables rules that prevent packets arriving on a host interface from reaching container addresses are not re-created. Once these rules have been removed, a remote host configured with a route to a Docker bridge network can access published ports, even when those ports were only published to a loopback address. Unpublished ports remain inaccessible. For example, following a firewalld reload on a Docker host with address `192.168.0.10` and a bridge network with subnet `172.17.0.0/16`, running the following command on another host in the local network will give it access to published ports on container addresses in that network: `ip route add 172.17.0.0/16 via 192.168.0.10`. Containers running in networks created with `--internal` or equivalent have no access to other networks. Containers that are only connected to these networks remain isolated after a firewalld reload. Where Docker Engine is not running in the host's network namespace, it is unaffected. Including, for example, Rootless Mode, and Docker Desktop. ### Patches Moby releases older than 28.2.0 are not affected. A fix is available in moby release 28.3.3. ### Workarounds After reloading firewalld, either: - Restart the docker daemon, - Re-create bridge networks, or - Use rootless mode. ### References https://firewalld.org/ https://firewalld.org/documentation/howto/reload-firewalld.html

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