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SeerrApplication

CVE-2026-27707

CRITICAL · 9.8 CVSS v3.1 Published 2026-02-27
Fix available
A fix is available. Upgrade to 3.1.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Seerr versions 2.0.0 through 3.0.0 contain a logic flaw in the POST /api/v1/auth/jellyfin endpoint that allows unauthenticated attackers to register new accounts by authenticating with an attacker-controlled Jellyfin server. The vulnerability only affects deployments where mediaServerType is PLEX, Jellyfin IP is unset (empty string), and newPlexLogin is enabled (all defaults).

MitigationUpgrade to Seerr version 3.1.0 or later. Alternatively, mitigate by configuring a non-empty Jellyfin IP address or disabling the newPlexLogin setting.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
SeerrApplication
Affected:>= 2.0.0, < 3.1.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Seerr version
    Access the application UI and check the version in Settings > About, or inspect the docker container/image version tag
    Affected if Version is >= 2.0.0 and < 3.1.0
  2. Check mediaServerType configuration
    Inspect Seerr configuration database or settings file for the mediaServerType value
    Affected if mediaServerType is set to PLEX
  3. Check Jellyfin IP setting
    Inspect Seerr configuration for the jellyfinIp or corresponding setting that stores the Jellyfin server IP address
    Affected if Jellyfin IP is empty or unset (null/blank)
  4. Check newPlexLogin setting
    Inspect Seerr configuration for the newPlexLogin boolean setting
    Affected if newPlexLogin is enabled (true/checked)

A user is affected if running Seerr 2.0.0-3.0.0 with mediaServerType set to PLEX, empty Jellyfin IP, and newPlexLogin enabled - all of which are default values.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 3.1.0 or later
Fixed in 3.1.0
Vendor patch github.com →
Interim mitigation

Upgrade to Seerr version 3.1.0 or later. Alternatively, mitigate by configuring a non-empty Jellyfin IP address or disabling the newPlexLogin setting.

Recommended fix High confidence

3.1.0

  1. Upgrade Seerr to version 3.1.0 or later by pulling the latest Docker image or using your preferred installation method
  2. After upgrading, verify that `settings.main.mediaServerType`, `settings.jellyfin.ip`, and `settings.main.newPlexLogin` are properly configured for your deployment
  3. Confirm the authentication guard logic flaw in `POST /api/v1/auth/jellyfin` is resolved by attempting the vulnerable flow (or verifying via code commit 4ae20684092b5b28527b23dfbc1a3417858fee8e that the fix is applied)
Caveat Review Seerr 3.1.0 release notes for any potential breaking changes before upgrading, as this is a minor version upgrade

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Seerr Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-27707 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data