Summary A flaw in Tauri's islocalurl() 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.

Details Vulnerable function:

rust #[cfg(any(windows, targetos = "android"))] let local = { let protocolurl = self.manager().tauriprotocolurl(useshttps); let maybeprotocol = currenturl .domain() .andthen(|d| d.splitonce('.')) // BUG: only splits on first dot .unwrapordefault() .0;

protocols.containskey(maybeprotocol) && scheme == protocolurl.scheme() };

Link: https://github.com/tauri-apps/tauri/blob/1ef6a119b1571d1da0acc08bdb7fd5521a4c6d52/crates/tauri/src/webview/mod.rs#L1680

splitonce('.') discards everything after the first .. For http://app.evil.com/, the extracted label is app. If the application has registered a protocol named app, protocols.containskey("app") returns true and the URL is classified as Origin::Local. The correct check must assert the full domain is exactly <protocol>.localhost.

PoC We created a proof of concept app that can be found here. The app registers a custom app:// protocol and exposes a ping command restricted to local origins only. It provides a button to open a URL in a WebView, pre-filled with https://app.robbe-bc9.workers.dev/, an attacker-controlled page that invokes ping on load. Because the domain's first label matches the registered app protocol, islocalurl() classifies it as a local origin and the command succeeds.

capabilities/main.json contains the following code, which only exposes ping locally:

json { "$schema": "../../../crates/tauri-schema-generator/schemas/capability.schema.json", "identifier": "main", "local": true, "windows": [""], "permissions": [ "sample:allow-ping" ] }

src/lib.rs contains the following code, to register a custom scheme:

rust tauri::Builder::default() .registerurischemeprotocol("app", |ctx, request| { ... })

Impact 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.

Tauri is a framework for building binaries for all major desktop platforms. The 1.4.0 release includes a regression on the Filesystem scope check for dotfiles on Unix. Previously dotfiles were not implicitly allowed by the glob wildcard scopes (eg. $HOME/), but a regression was introduced when a configuration option for this behavior was implemented. Only Tauri applications using wildcard scopes in the fs endpoint are affected. The regression has been patched on version 1.4.1.

Tauri is a framework for building binaries for all major desktop platforms. In versions prior to 1.0.7 and 1.1.2, Tauri is vulnerable to an Incorrectly-Resolved Name. Due to incorrect escaping of special characters in paths selected via the file dialog and drag and drop functionality, it is possible to partially bypass the fs scope definition. It is not possible to traverse into arbitrary paths, as the issue is limited to neighboring files and sub folders of already allowed paths. The impact differs on Windows, MacOS and Linux due to different specifications of valid path characters. This bypass depends on the file picker dialog or dragged files, as user selected paths are automatically added to the allow list at runtime. A successful bypass requires the user to select a pre-existing malicious file or directory during the file picker dialog and an adversary controlled logic to access these files. The issue has been patched in versions 1.0.7, 1.1.2 and 1.2.0. As a workaround, disable the dialog and fileDropEnabled component inside the tauri.conf.json.