In add-on mode, the ha-mcp settings UI routes are mounted both under the MCP secret path and at the bare root of the published port (:9583), so Home Assistant ingress can serve the "Open Web UI" button. The root-mounted routes perform no authentication — no secret, no Origin check, no CSRF token — so any client that can reach :9583 without the MCP secret can invoke them.
When ENABLE_YAML_CONFIG_EDITING=true, every ha_config_set_yaml call backs up the pre-edit file to <config>/www/yaml_backups/, which Home Assistant serves at /local/ with no authentication. Anyone who can reach the HA web interface can download the most recent pre-edit configuration.yaml (or other YAML file) — typically containing plaintext MQTT passwords, REST credentials, webhook IDs, geofence coordinates, and shell_command definitions — with zero credentials.
The ha-mcp OAuth consent form (beta feature) accepts a user-supplied ha_url and makes a server-side HTTP request to {ha_url}/api/config with no URL validation. An unauthenticated attacker can submit arbitrary URLs to perform internal network reconnaissance via an error oracle. Two additional code paths in OAuth tool calls (REST and WebSocket) are affected by the same primitive. The primary deployment method (private URL with pre-configured HOMEASSISTANT_TOKEN) is not affected.
The ha-mcp OAuth consent form renders user-controlled parameters via Python f-strings with no HTML escaping. An attacker who can reach the OAuth endpoint and convince the server operator to follow a crafted authorization URL could execute JavaScript in the operator's browser. This affects only users running the beta OAuth mode (ha-mcp-oauth), which is not part of the standard setup and requires explicit configuration.