CVE-2026-63640MagicMirror² is an open source modular smart mirror platform. Prior to 2.37.0, when hideConfigSecrets is enabled, the catch-all socket dispatcher in js/node_helper.js passes every inbound object payload through replaceSecretPlaceholder in js/server_functions.js before invoking socketNotificationReceived. A client connected to a loaded module namespace can submit a SECRET_API_KEY placeholder, causing the server to replace it with the corresponding process environment value. The default weather helper accepts INIT_WEATHER, copies the attacker-controlled instanceId, and returns it in WEATHER_ERROR, providing an echo path for the expanded secret. This reverses the intended one-way redaction boundary and can disclose API tokens, credentials, or service keys stored in SECRET_ variables. This issue is fixed in version 2.37.0.