Bazarr: Plex OAuth API namespace is entirely unauthenticated, allowing config tampering, integration takeover and server-side request forgery

Bazarr is a companion application to Sonarr and Radarr. Prior to 1.5.7-beta.14, the api_ns_plex namespace in bazarr/api/plex/oauth.py omits @authenticate on its Resource handlers, while normal APIs require an API key and no global authentication hook compensates. Anonymous callers can invoke POST /api/plex/oauth/logout to clear credentials and disable the integration, or POST /api/plex/apikey to persist an attacker-selected key, without a PIN, account or state precondition. POST /api/plex/oauth/pin and GET /api/plex/oauth/pin/<pin_id>/check additionally allow an attacker who completes a PIN with an attacker-controlled Plex account to bind that account's token to the instance. PlexPinCheck skips state validation when state_param is absent and merely logs a mismatch without stopping execution. POST /api/plex/select-server, POST /api/plex/oauth/servers, POST /api/plex/webhook/create, POST /api/plex/webhook/delete and POST /api/plex/encrypt-apikey expose further write_config() operations. Attacker-controlled server URLs feed later outbound requests carrying the configured API key in X-Plex-Token, enabling server-side request forgery and credential exposure in addition to persistent configuration tampering and integration denial of service. Version 1.5.7-beta.14 closes the anonymous API-mutation path by adding authentication; complete OAuth state validation is not established and remains a separate residual for curator review.