Impact

djust's LiveViewConsumer mounts a LiveView over a WebSocket. When a view is gated (loginrequired / permissionrequired, or an onmount hook that returns a redirect) and the connecting user is not authorized, the consumer sent the client a {"type":"navigate","to":...} redirect frame and then returned — without closing the socket and without clearing self.viewinstance. Only the PermissionDenied branch closed the connection (close(4403)).

A real browser obeys the navigate frame and leaves, hiding the problem. A raw WebSocket client that ignores the redirect keeps an open, mounted socket. Because handleevent did not re-check authentication/authorization after mount, that client could then send {"type":"event", ...} frames and invoke any @eventhandler method on the gated view with no authenticated session — an authentication bypass on the live mutation path.

Who is affected: apps that expose LiveViews gated by loginrequired / permissionrequired / a redirecting onmount hook, where the gated view's event handlers perform sensitive reads or mutations and do not independently re-verify the user. Exploitation requires a non-browser WebSocket client and knowledge (or enumeration) of the view path and event names.

Patches

Fixed in djust 1.0.4 (commit 1ae8aa9, PR #1780). Both the auth-redirect and onmount-hook-redirect branches of handlemount now send the navigate frame and then close(code=4403) and clear self.viewinstance, mirroring the existing PermissionDenied branch. Public / authorized mounts are unchanged. The same path is reachable via handleliveredirectmount (which delegates to handlemount) and is covered by the same fix.

1.0.4 also adds an opt-in defense-in-depth control, LIVEVIEWCONFIG['reauthonevent'] = True (default OFF), which re-resolves the user from the session and re-runs the view's auth check on every event for gated views.

Workarounds

Upgrade to 1.0.4. If you cannot upgrade immediately, on affected versions ensure that every @eventhandler on a gated LiveView independently verifies the request user is authenticated and authorized (e.g. check request.user.isauthenticated / permissions at the top of each handler), since the framework does not re-check after mount on < 1.0.4. Alternatively, override the consumer's handlemount to await self.close(code=4403) after emitting an auth redirect.

Proof of concept

Using Channels' WebsocketCommunicator against LiveViewConsumer.asasgi() with an anonymous scope, mount a loginrequired view: the server emits a navigate frame but the socket stays open. Sending a subsequent {"type":"event", "handler":"<mutatinghandler>", ...} frame reaches the handler and executes it without an authenticated session. On 1.0.4 the socket is closed with code 4403 immediately after the redirect and the event frame is rejected. (Regression test: tests/testwsauthclosesocket.py.)

Credits

Discovered internally during the djust v1.1.0 WebSocket-auth security review.