Companion App Android
Monthly
Cross-origin JavaScript injection in Home Assistant Companion apps for Android (before 2026.4.4) and iOS (before 2026.4.1) allows a malicious iframe loaded inside the app's WebView to execute arbitrary JavaScript in the Home Assistant frontend's origin and steal the signed-in user's access token. The flaw stems from exposing the native JavaScript bridge (window.externalApp on Android, webkit.messageHandlers.getExternalAuth on iOS) to all frames combined with unsanitized callback identifier interpolation. No public exploit identified at time of analysis, and the issue is not in CISA KEV.
Cross-origin JavaScript injection in Home Assistant Companion apps for Android (before 2026.4.4) and iOS (before 2026.4.1) allows a malicious iframe loaded inside the app's WebView to execute arbitrary JavaScript in the Home Assistant frontend's origin and steal the signed-in user's access token. The flaw stems from exposing the native JavaScript bridge (window.externalApp on Android, webkit.messageHandlers.getExternalAuth on iOS) to all frames combined with unsanitized callback identifier interpolation. No public exploit identified at time of analysis, and the issue is not in CISA KEV.