CVE-2026-27707

Seerr is an open-source media request and discovery manager for Jellyfin, Plex, and Emby. Starting in version 2.0.0 and prior to version 3.1.0, an authentication guard logic flaw in `POST /api/v1/auth/jellyfin` allows an unauthenticated attacker to register a new Seerr account on any Plex-configured instance by authenticating with an attacker-controlled Jellyfin server. The attacker receives an authenticated session and can immediately use the application with default permissions, including the ability to submit media requests to Radarr/Sonarr. Any Seerr deployment where all three of the following are true may be vulnerable: `settings.main.mediaServerType` is set to `PLEX` (the most common deployment).; `settings.jellyfin.ip` is set to `""` (default, meaning Jellyfin was never configured); and `settings.main.newPlexLogin` is set to `true` (default). Jellyfin-configured and Emby-configured deployments are not affected. Version 3.1.0 of Seerr fixes this issue.

Seerr is an open-source media request and discovery manager for Jellyfin, Plex, and Emby. Starting in version 2.0.0 and prior to version 3.1.0, an authentication guard logic flaw in `POST /api/v1/auth/jellyfin` allows an unauthenticated attacker to register a new Seerr account on any Plex-configured instance by authenticating with an attacker-controlled Jellyfin server. The attacker receives an authenticated session and can immediately use the application with default permissions, including the ability to submit media requests to Radarr/Sonarr. Any Seerr deployment where all three of the following are true may be vulnerable: `settings.main.mediaServerType` is set to `PLEX` (the most common deployment).; `settings.jellyfin.ip` is set to `""` (default, meaning Jellyfin was never configured); and `settings.main.newPlexLogin` is set to `true` (default). Jellyfin-configured and Emby-configured deployments are not affected. Version 3.1.0 of Seerr fixes this issue.

Seerr es un gestor de solicitudes y descubrimiento de medios de código abierto para Jellyfin, Plex y Emby. A partir de la versión 2.0.0 y antes de la versión 3.1.0, una falla lógica en la protección de autenticación en 'POST /API/v1/auth/jellyfin' permite a un atacante no autenticado registrar una nueva cuenta de Seerr en cualquier instancia configurada con Plex autenticándose con un servidor Jellyfin controlado por el atacante. El atacante recibe una sesión autenticada y puede usar inmediatamente la aplicación con permisos predeterminados, incluida la capacidad de enviar solicitudes de medios a Radarr/Sonarr. Cualquier implementación de Seerr donde se cumplan las tres condiciones siguientes puede ser vulnerable: 'settings.main.mediaServerType' está configurado como 'PLEX' (la implementación más común).; 'settings.jellyfin.ip' está configurado como '""' (predeterminado, lo que significa que Jellyfin nunca fue configurado); y 'settings.main.newPlexLogin' está configurado como 'true' (predeterminado). Las implementaciones configuradas con Jellyfin y Emby no se ven afectadas. La versión 3.1.0 de Seerr soluciona este problema.