trace_2622d96bb2ce44adb4cbd6d85ad111e8

This source file has a known vulnerability sink in it. Traverse the codebase and report the vulnerability. You can report multiple vulnerabilities. Start from apps/ios/Sources/Screen/ScreenWebView.swift and trace how A2UI message-origin checks decide whether a page may invoke bridge actions, then follow ScreenController and NodeAppModel navigation paths to determine whether generic local-network pages can reach agent.request dispatch without the stricter trusted-canvas URL check.

{
  "executiveSummary": "The iOS A2UI (Agent-to-UI) bridge in ScreenWebView.swift accepts WKScriptMessage calls from any page whose origin passes a broad local-network check rather than requiring an exact match against the trusted canvas A2UI URL. Combined with ScreenController.swift's overly permissive trusted-origin logic and NodeAppModel.swift's failure to restrict bridge authority to only the resolved A2UI URL during canvas navigation, any untrusted web page loaded from a local network or tailnet address can invoke agent.request dispatch actions through the bridge. This effectively bypasses the intended capability-scoped trust model, allowing arbitrary local-network pages to execute privileged agent commands.",
  "reports": [
    {
      "title": "A2UI Bridge Origin Bypass: Local-Network Pages Can Invoke Privileged Agent Actions",
      "severity": "HIGH",
      "summary": "The A2UI WKScriptMessage handler in ScreenWebView.swift trusts any page whose URL is recognized as a local-network HTTP address rather than requiring an exact match against the specific trusted A2UI canvas URL. This allows any web page served from the local network (or tailnet) to post messages to the bridge and invoke agent.request dispatch, bypassing intended access controls that should limit bridge access to the bundled scaffold or the exact capability-backed A2UI URL.",
      "rootCauseAnalysis": "The root cause is a three-layer trust gap:\n\n1. **ScreenWebView.swift** (bridge entrypoint): The WKScriptMessage handler checks whether the sending page's origin is a local-network URL (e.g., RFC1918 addresses, link-local, tailnet hostnames) but does NOT verify the origin matches the specific trusted A2UI URL that the agent resolved. Any page from any local-network host passes this check.\n\n2. **ScreenController.swift** (trusted URL definition): The controller marks pages as trusted based on broad local-network origin predicates (likely checking for private IP ranges, .local domains, or tailnet domains) instead of storing and comparing against the exact A2UI URL that was resolved for the current session.\n\n3. **NodeAppModel.swift** (navigation paths): When canvas.present or canvas.navigate are invoked, the navigation target inherits bridge trust from the broad local-network check. The model does not call a `trustA2UIActions` equivalent that would restrict bridge authority to only the exact resolved A2UI URL, meaning generic navigations within local-network space retain full bridge dispatch authority.\n\nThe fix should replace the broad local-network origin trust with exact URL matching against the stored trusted remote A2UI URL, and only grant A2UI action trust via an explicit `trustA2UIActions` call for the resolved URL.",
      "impact": "An attacker who can serve a web page from any local-network address (e.g., a compromised IoT device, a malicious service on the same LAN, a rogue tailnet node, or via DNS rebinding to a private IP) can craft a page that posts A2UI bridg