{"id":"CVE-2026-55571","aliases":["GHSA-xx4j-w367-7247","PYSEC-2026-3829"],"title":"djust authentication bypass: a login_required / on_mount LiveView mount redirect does not close the WebSocket, allowing an unauthenticate…","summary":"djust authentication bypass: a login_required / on_mount LiveView mount redirect does not close the WebSocket, allowing an unauthenticated client to dispatch event-handler calls","severity":"high","cvss":8.2,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N","vendor":"djust","product":"djust","ecosystem":"pip","affected":["djust < 1.0.4"],"patched":["djust 1.0.4"],"published":"2026-08-25","updated":"2026-09-10","sourceUpdated":"2026-09-10T12:25:27.409576998Z","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-xx4j-w367-7247","references":[{"url":"https://github.com/djust-org/djust/security/advisories/GHSA-xx4j-w367-7247"},{"url":"https://github.com/djust-org/djust/pull/1780"},{"url":"https://github.com/djust-org/djust/commit/1ae8aa9246b80477de7ddc4d90319a3b267bef04"},{"url":"https://github.com/djust-org/djust"},{"url":"https://pypi.org/project/djust"},{"url":"https://github.com/advisories/GHSA-xx4j-w367-7247"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55571"},{"url":"https://github.com/djust-org/djust/releases/tag/v1.0.4","label":"security-advisories@github.com"}],"tags":["osv","pip","nvd","ghsa"],"epss":0.00283,"epssPercentile":0.21029,"cwe":["CWE-285","CWE-306"],"ingestedAt":"2026-08-25T16:28:50.940Z","slug":"CVE-2026-55571","body":"## Overview\n\n### Impact\n\ndjust'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)`).\n\nA 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.\n\n**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.\n\n### Patches\n\nFixed 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.\n\n1.0.4 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.\n\n### Workarounds\n\nUpgrade 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.\n\n### Proof of concept\n\nUsing 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`.)\n\n### Credits\n\nDiscovered internally during the djust v1.1.0 WebSocket-auth security review.\n\n## Affected packages\n\n- `djust < 1.0.4`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `djust 1.0.4`","depth":"twilight","depthScore":45,"depthScoreParts":{"impact":45.1,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}