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JellyfinApplication

CVE-2026-35031

HIGH · 8.8 CVSS v3.1 Published 2026-04-14
Fix available
A fix is available. Upgrade to 10.11.7 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click

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
Jellyfin is an open source self hosted media server. Versions prior to 10.11.7 contain a vulnerability chain in the subtitle upload endpoint (POST /Videos/{itemId}/Subtitles), where the Format field is not validated, allowing path traversal via the file extension and enabling arbitrary file write. This arbitrary file write can be chained into arbitrary file read via .strm files, database extraction, admin privilege escalation, and ultimately remote code execution as root via ld.so.preload. Exploitation requires an administrator account or a user that has been explicitly granted the "Upload Subtitles" permission. This issue has been fixed in version 10.11.7. If users are unable to upgrade immediately, they can grant non-administrator users Subtitle upload permissions to reduce attack surface.

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

The subtitle upload endpoint in Jellyfin versions prior to 10.11.7 fails to validate the Format field, allowing path traversal through the file extension. This enables arbitrary file write, which can be chained with .strm files to achieve arbitrary file read, database extraction, admin privilege escalation, and ultimately remote code execution as root via ld.so.preload.

MitigationUpgrade to Jellyfin 10.11.7 or later. If immediate upgrade is not possible, restrict subtitle upload permissions to trusted administrators only and consider network isolation.

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
JellyfinApplication
Affected:< 10.11.7

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/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 installed Jellyfin version
    Access the Jellyfin dashboard and navigate to Dashboard > General, or query the /System/Info API endpoint. The version number is displayed prominently.
    Affected if The installed version is below 10.11.7 (for example, 10.11.6, 10.10.x, or earlier)
  2. Verify subtitle upload endpoint is accessible
    Confirm that the Jellyfin server is running and network-accessible. The vulnerable endpoint is POST /Videos/{itemId}/Subtitles - check if this endpoint responds to requests from authenticated users.
    Affected if The subtitle upload API endpoint is reachable and responds to requests (indicating the feature is active)
  3. Review user permissions for subtitle uploads
    Navigate to Dashboard > Users in the Jellyfin admin panel. Examine which users have permissions to upload or manage subtitles for media items.
    Affected if Any user account (especially untrusted or non-admin accounts) has permissions to upload subtitles to video library items
  4. Check for existing uploaded subtitle files
    Inspect the media library directories on the server for any .srt, .ass, or other subtitle files that may have been uploaded by users.
    Affected if Subtitle files exist that were uploaded through the web interface, indicating the feature has been used

You are affected if your Jellyfin version is below 10.11.7 AND any user with subtitle upload permissions can access the vulnerable endpoint.

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 10.11.7 or later
Fixed in 10.11.7
Interim mitigation

Upgrade to Jellyfin 10.11.7 or later. If immediate upgrade is not possible, restrict subtitle upload permissions to trusted administrators only and consider network isolation.

Recommended fix High confidence

10.11.7

  1. Back up the Jellyfin data directory before upgrading
  2. Stop the Jellyfin service
  3. Upgrade Jellyfin to version 10.11.7 using your package manager or by downloading from the official Jellyfin releases
  4. Start the Jellyfin service
  5. Verify the upgrade was successful by checking the Jellyfin server info page

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

Fix this in Jellyfin Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.

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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-2026-35031 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