Home Assistant Companion: `homeassistant://invite` Deep Link Credential Phishing

Summary

Home Assistant is open source home automation software focused on local control and privacy. Prior to 2026.6.1, the Android Companion app is vulnerable to an open redirect. The app passes the URL fragment from a homeassistant://invite deep link into the onboarding flow without ever displaying the destination hostname. Because no screen in the invitation or onboarding flow shows the parsed server URL before onboarding commits to it, a victim has no way to distinguish a legitimate invite from a malicious one. An attacker can craft an invite so that a single tap on the legitimate-looking "Connect to my Home Assistant server" button opens their /auth/authorize endpoint in the URL-less onboarding WebView, presenting a look-alike login page that captures the victim's credentials. Since invitations are intended to onboard brand-new users, targets are especially unlikely to notice the substitution. This issue is fixed in version 2026.6.1.