Vulnerability Description
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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Seerr | Seerr | >= 2.0.0, < 3.1.0 |
Related Weaknesses (CWE)
References
- https://github.com/seerr-team/seerr/commit/4ae20684092b5b28527b23dfbc1a3417858fePatch
- https://github.com/seerr-team/seerr/releases/tag/v3.1.0Release Notes
- https://github.com/seerr-team/seerr/security/advisories/GHSA-rc4w-7m3r-c2f7Vendor AdvisoryExploit
FAQ
What is CVE-2026-27707?
CVE-2026-27707 is a vulnerability with a CVSS score of 7.3 (HIGH). 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...
How severe is CVE-2026-27707?
CVE-2026-27707 has been rated HIGH with a CVSS base score of 7.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-27707?
Check the references section above for vendor advisories and patch information. Affected products include: Seerr Seerr.