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Path TraversalWeakness · CWE-22

CVE-2026-49247

HIGH · 8.8 CVSS v3.1 Published 2026-06-24
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click 8 weeks old

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. From 10.9.0 until 10.11.10, the POST /ClientLog/Document endpoint accepts the Authorization header's Client and Version fields and uses them unsanitized as components of the on-disk filename when persisting client-uploaded log documents. As a result, any authenticated non-admin user can include ../ sequences in the Client field to cause Jellyfin to write attacker-controlled content to arbitrary paths reachable by the Jellyfin service user, with a forced .log suffix. This vulnerability is fixed in 10.11.10.

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

Jellyfin versions 10.9.0 through 10.11.10 contain a path traversal vulnerability in the POST /ClientLog/Document endpoint. The endpoint accepts the Client field from the Authorization header and uses it unsanitized in file paths, allowing authenticated non-admin users to inject ../ sequences and write attacker-controlled content with a .log suffix to arbitrary locations on the filesystem accessible by the Jellyfin service account.

MitigationUpgrade Jellyfin to version 10.11.10 or later where the vulnerability is fixed. If immediate patching is not possible, consider network segmentation and monitoring for suspicious log upload patterns containing path traversal sequences.

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

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. Identify installed Jellyfin version
    Access the Jellyfin dashboard and navigate to Dashboard > General, or query the server's API endpoint /System/Info to retrieve the Version field. Compare this version number to 10.11.10.
    Affected if The installed version is below 10.11.10.
  2. Verify authentication is enabled
    Confirm that Jellyfin requires authentication for API access. Check in Dashboard > Users that at least one non-admin user account exists and that authentication is enforced.
    Affected if Non-admin user accounts exist and can authenticate to the server.
  3. Confirm ClientLog endpoint is accessible
    Test access to the POST /ClientLog/Document endpoint by sending an authenticated request (with a valid API key or session token) as a non-admin user. Verify the endpoint responds without returning a 403 Forbidden error.
    Affected if Non-admin authenticated users can reach the /ClientLog/Document endpoint.
  4. Review recent ClientLog submissions
    Inspect the server's log directory (typically found under the Jellyfin data/logs or program data/Jellyfin/logs folder) for .log files with unexpected path traversal patterns (containing ../ sequences) in filenames.
    Affected if Log files exist with ../ sequences in their names, indicating exploitation attempts.

The environment is affected if Jellyfin version is below 10.11.10 and non-admin authenticated users have access to the /ClientLog/Document 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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Jellyfin to version 10.11.10 or later where the vulnerability is fixed. If immediate patching is not possible, consider network segmentation and monitoring for suspicious log upload patterns containing path traversal sequences.

Recommended fix High confidence

10.11.10

  1. 1. Back up your Jellyfin configuration and database before upgrading.
  2. 2. Upgrade Jellyfin to version 10.11.10 or later using your installation method (e.g., package manager, Docker, or manual update).
  3. 3. Verify the upgrade was successful by checking the Jellyfin server version.
  4. 4. Confirm the /ClientLog/Document endpoint now properly sanitizes the Client and Version fields from the Authorization header.
Caveat Review Jellyfin release notes for 10.11.x as minor version upgrades may include configuration or feature changes.

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

Have this fixed 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-2026-49247 in production — separate from our analysis above.

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