GHSA-xx4j-w367-7247

### Impact

djust's `LiveViewConsumer` mounts a `LiveView` over a WebSocket. When a view is gated (`login_required` / `permission_required`, or an `on_mount` 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 `return`ed — **without closing the socket and without clearing `self.view_instance`**. 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 `handle_event` did not re-check authentication/authorization after mount, that client could then send `{"type":"event", ...}` frames and invoke any `@event_handler` method on the gated view **with no authenticated session** — an authentication bypass on the live mutation path.

**Who is affected:** apps that expose `LiveView`s gated by `login_required` / `permission_required` / a redirecting `on_mount` 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 `on_mount`-hook-redirect branches of `handle_mount` now send the navigate frame **and then `close(code=4403)` and clear `self.view_instance`**, mirroring the existing `PermissionDenied` branch. Public / authorized mounts are unchanged. The same path is reachable via `handle_live_redirect_mount` (which delegates to `handle_mount`) and is covered by the same fix.

1.0.4 also adds an opt-in defense-in-depth control, `LIVEVIEW_CONFIG['reauth_on_event'] = 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 `@event_handler` on a gated `LiveView` independently verifies the request user is authenticated and authorized** (e.g. check `request.user.is_authenticated` / 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 `handle_mount` to `await self.close(code=4403)` after emitting an auth redirect.

### Proof of concept

Using Channels' `WebsocketCommunicator` against `LiveViewConsumer.as_asgi()` with an **anonymous** scope, mount a `login_required` view: the server emits a `navigate` frame but the socket stays open. Sending a subsequent `{"type":"event", "handler":"<mutating_handler>", ...}` 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/test_ws_auth_close_socket.py`.)

### Credits

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