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. A missing authorization vulnerability has been identified in the application starting in version 2.7.0 and prior to version 3.1.0. It allows authenticated users to access and modify data belonging to other users. This issue is due to the absence of the `isOwnProfileOrAdmin()` middleware on several push subscription API routes. Version 3.1.0 fixes the issue.

Seerr is an open-source media request and discovery manager for Jellyfin, Plex, and Emby. Prior to version 3.1.0, the `GET /api/v1/user/:id` endpoint returns the full settings object for any user, including Pushover, Pushbullet, and Telegram credentials, to any authenticated requester regardless of their privilege level. This vulnerability can be exploited alone or combined with the reported unauthenticated account creation vulnerability, CVE-2026-27707. When combined, the two vulnerabilities create a zero-prior-access chain that leaks third-party API credentials for all users, including administrators. Version 3.1.0 contains a fix for both this vulnerability and for CVE-2026-27707.