CVE-2026-42184

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.

Details

Vulnerable function:

#[cfg(any(windows, target_os = "android"))]
let local = {
  let protocol_url = self.manager().tauri_protocol_url(uses_https);
  let maybe_protocol = current_url
    .domain()
    .and_then(|d| d.split_once('.'))  // BUG: only splits on first dot
    .unwrap_or_default()
    .0;

  protocols.contains_key(maybe_protocol) && scheme == protocol_url.scheme()
};

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

split_once('.') 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.contains_key("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, is_local_url() classifies it as a local origin and the command succeeds.

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

{
  "$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:

tauri::Builder::default()
  .register_uri_scheme_protocol("app", |_ctx, _request| { ... })

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.

Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.

CVE-2026-42184 has a CVSS score of 8.8 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.11.1); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-42184? CVE-2026-42184 is a medium-severity server-side request forgery (SSRF) vulnerability in tauri (rust), affecting versions >= 2.0.0, <= 2.11.0. It is fixed in 2.11.1. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
2. How severe is CVE-2026-42184? CVE-2026-42184 has a CVSS score of 8.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of tauri are affected by CVE-2026-42184? tauri (rust) versions >= 2.0.0, <= 2.11.0 is affected.
4. Is there a fix for CVE-2026-42184? Yes. CVE-2026-42184 is fixed in 2.11.1. Upgrade to this version or later.
5. Is CVE-2026-42184 exploitable, and should I be worried? Whether CVE-2026-42184 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-42184 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-42184? Upgrade tauri to 2.11.1 or later.