CVE-2026-42184: Tauri has an Origin Confusion Issue that Allows Remote Pages to Invoke Local-Only IPC Commands

A flaw in Tauri’s is_local_url() function causes it to incorrectly classify remote URLs as trusted local origins on Windows and Android. On these systems, Tauri maps custom URI scheme protocols to http://<scheme>.localhost/ because those platforms’ WebView implementations cannot serve custom URI schemes directly.

The issue is that Tauri’s check to see if the origin is local, only checks the first subdomain of the URL. An attacker can abuse this by hosting a page on a domain whose subdomain matches the custom scheme of the application (e.g. http://app.attacker.com/)."

Example:

• Local URL: app://localhost/ → on Android/Windows: http://app.localhost/
• The check passes for any URL starting with http://app., including http://app.evil.com/

As a result, the attacker page can invoke backend commands that the developer intended to be accessible only to the app’s own frontend and that are explicitly restricted from being called by external or remote origins.