Because the add-on operates in host network mode, this configuration exposes the dashboard directly to the host's LAN interface. Any device on the same local network as the Home Assistant host can access the dashboard without authentication. Given that the dashboard's capabilities include running arbitrary Python code and system shell commands, an attacker can leverage this exposure to gain full remote code execution on the Home Assistant host, including control over the configuration directory and managed ESPHome devices. The vulnerability was present by default in all host-network installs prior to version 1.0.10.

Attack Chain

1. Attacker performs network discovery on the local area network to identify the Home Assistant host IP address.
2. Attacker probes the Home Assistant host on the known add-on ingress port to identify the ESPHome dashboard service.
3. Attacker sends an unauthenticated HTTP GET request to the ingress port, confirming access to the dashboard interface.
4. Attacker navigates the dashboard to the compile/validation section, which supports arbitrary code execution.
5. Attacker uploads a malicious ESPHome configuration file containing an external_components definition with embedded Python payloads.
6. Attacker triggers the dashboard compile function, causing the backend to execute the injected Python code or shell commands with the privileges of the Home Assistant add-on process.
7. Attacker achieves persistent access or full system control by deploying a reverse shell or modifying the Home Assistant configuration files.

Impact

Successful exploitation results in full compromise of the Home Assistant add-on and the underlying host. The attacker gains the ability to read or modify arbitrary files within the mounted configuration and data directories, and can execute system-level commands. This vulnerability affects any Home Assistant instance running the host-networked ESPHome add-on, posing a critical risk to users on shared or untrusted local networks.

Recommendation

Prioritized actions for security and infrastructure teams:

• Immediately upgrade the esphome container to include esphome-device-builder version 1.0.10 or later.
• Implement network-layer access control on the Home Assistant host to restrict access to the ESPHome ingress port, ensuring only the local loopback and the supervisor gateway (172.30.32.1) are permitted.
• Audit the Home Assistant configuration directory for unauthorized modifications or newly created files that may indicate previous exploitation of this interface.
• Segment the Home Assistant host from untrusted IoT devices or guest network segments to mitigate the risk of unauthorized local network access.