CVE-2026-27707
HIGHDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Exploit Intelligence
Moderate risk: more likely to be exploited than 41% of all known CVEs.
References
Related Vulnerabilities
Other CWE-288 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2023-42793 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2024-1709 | Critical | 10.0 | 100% | KEV + Ransom | Fix |
| CVE-2024-27198 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2025-4427 | Medium | 5.3 | 100% | KEV | Fix |
| CVE-2024-55591 | Critical | 9.8 | 98% | KEV + Ransom | Fix |
| CVE-2023-46747 | Critical | 9.8 | 97% | KEV + Ransom | - |
Common questions
How do I fix CVE-2026-27707?
Upgrade seerr to 3.1.0 or later.
Is CVE-2026-27707 being actively exploited?
Not that we know of. CVE-2026-27707 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.51% is the estimated probability that it will be exploited in the next 30 days. That is higher than 41% of all scored CVEs.
How severe is CVE-2026-27707?
CVE-2026-27707 has a CVSS v3 base score of 7.3, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-27707 affect?
Published advisories record a fix for seerr (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2026-27707
Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-04.