The MLX inference backend in Docker Model Runner on macOS uses the MLX-LM library, which unconditionally imports and executes arbitrary Python files from model directories via the model_file configuration field in config.json. When a model's config.json specifies a model_file pointing to a Python file, MLX-LM uses importlib to load and execute it with no trust_remote_code gate or equivalent safety check. The MLX backend runs without sandboxing, resulting in arbitrary code execution on the Docker host as the Docker Desktop user. Any container on the Docker network can trigger this by calling the model-runner.docker.internal API to pull a malicious model from an attacker-controlled OCI registry and request inference.

The Docker CLI --use-api-socket flag bypasses Enhanced Container Isolation (ECI) restrictions in Docker Desktop. When ECI is enabled, Docker socket mounts from containers are denied unless explicitly allowed via the admin-settings configuration. However, the --use-api-socket flag adds the Docker socket mount via the HostConfig.Mounts field rather than the HostConfig.Binds field. The ECI enforcement in the Docker Desktop API proxy only inspected Binds, allowing the mount to pass unchecked. This grants a container full access to the Docker Engine socket and, if the host user has logged in to container registries, their authentication credentials. A local attacker with the ability to run Docker CLI commands can exploit this to escape ECI restrictions, access the Docker Engine, and potentially escalate privileges.