Moby firewalld reload makes published container ports accessible from remote hostsGHSA-x4rx-4gw3-53p4
MEDIUMFix: moby/moby#50506GHSA-x4rx-4gw3-53p4 is a medium-severity (CVSS 4.6) CWE-909 vulnerability in github.com/docker/docker. A fix is available for github.com/docker/docker — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-x4rx-4gw3-53p4.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
github.com/docker/dockerReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
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. The Moby daemon component (dockerd), which is developed as 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 Unpublished ports remain inaccessible.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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/docker/docker | ≥ 28.2.0&&< 28.3.3 | 28.3.3go get github.com/docker/docker@v28.3.3 |
Affected Products
mobymobyprojectDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/docker/docker, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/docker/docker to 28.3.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-x4rx-4gw3-53p4 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for GHSA-x4rx-4gw3-53p4 (CC BY 4.0)
Frequently Asked Questions
Is GHSA-x4rx-4gw3-53p4 in your dependencies?
Find it across Go, including transitive dependencies.