CVE-2026-27707 (GCVE-0-2026-27707)
Vulnerability from cvelistv5 – Published: 2026-02-27 19:29 – Updated: 2026-02-27 20:22
VLAI
EPSS
VEX
Title
Plex-configured Seerr instances vulnerable to unauthenticated account registration via Jellyfin authentication endpoint
Summary
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.
Severity
7.3 (High)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-02-27 20:22 UTC
CWE
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/seerr-team/seerr/security/advi… | x_refsource_CONFIRM |
| https://github.com/seerr-team/seerr/commit/4ae206… | x_refsource_MISC |
| https://github.com/seerr-team/seerr/releases/tag/v3.1.0 | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| seerr-team | seerr |
Affected:
>= 2.0.0, < 3.1.0
|
guessed |
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