djust has Cross-Site Request Forgery on the Server-Sent-Events transport: a cross-origin page can drive a victim-authenticated SSE session

djust provides Phoenix LiveView-style reactive server-side rendering for Django with Rust-powered performance. Prior to version 1.0.7, the SSE client→server POST endpoints are `@csrf_exempt` and the SSE GET stream endpoint had no Origin check, so a cross-origin page could drive a victim-cookie-authenticated SSE session: force the victim's browser to GET the stream URL (which creates and mounts a LiveView as the victim) and POST to the message endpoint with `credentials: include` to fire state-changing event handlers as the victim. The URL `session_id` is client-chosen (validated only for UUID *format*), so it is not a CSRF token, and a JSON body sent as `text/plain` is a CORS simple request with no preflight. The issue is fixed in 1.0.7. All three SSE endpoints validate the request `Origin` against `ALLOWED_HOSTS` (mirroring the WebSocket CSWSH defense) and reject cross-origin requests with 403; the POST endpoints additionally require `Content-Type: application/json` (415 otherwise), closing the `text/plain` simple-request bypass. As a workaround, disable the SSE transport, or front it with a proxy that enforces an Origin allowlist.

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