CVE-2026-27707
Plex-configured Seerr instances vulnerable to unauthenticated account registration via Jellyfin authentication endpoint
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.
| CWE | CWE-288 CWE-807 |
| Vendor | seerr-team |
| Product | seerr |
| Published | Feb 27, 2026 |
| Last Updated | Feb 27, 2026 |
Get instant alerts for seerr-team seerr
Be the first to know when new high vulnerabilities affecting seerr-team seerr are published — delivered to Slack, Telegram or Discord.
CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L