CVE-2026-35031
Received Received - Intake
Path Traversal and RCE in Jellyfin Subtitle Upload Endpoint

Publication date: 2026-04-14

Last updated on: 2026-04-23

Assigner: GitHub, Inc.

Description
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.
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Meta Information
Published
2026-04-14
Last Modified
2026-04-23
Generated
2026-06-16
AI Q&A
2026-04-15
EPSS Evaluated
2026-06-14
NVD
CVE-2026-35031
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
jellyfin jellyfin to 10.11.7 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-22 The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
CWE-187 The product performs a comparison that only examines a portion of a factor before determining whether there is a match, such as a substring, leading to resultant weaknesses.
CWE-20 The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
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Executive Summary

This vulnerability exists in Jellyfin versions prior to 10.11.7 in the subtitle upload endpoint (POST /Videos/{itemId}/Subtitles). The Format field is not properly validated, which allows an attacker to perform path traversal through the file extension. This enables arbitrary file write on the server.

The arbitrary file write can be chained to arbitrary file read via .strm files, extraction of the database, escalation to administrator privileges, and ultimately remote code execution as root through manipulation of ld.so.preload.

Exploitation requires either an administrator account or a user explicitly granted the "Upload Subtitles" permission.

The issue was fixed in version 10.11.7. Users unable to upgrade immediately can reduce the attack surface by granting subtitle upload permissions only to non-administrator users.

Mitigation Strategies

To mitigate this vulnerability, upgrade Jellyfin to version 10.11.7 or later where the issue is fixed.

If immediate upgrade is not possible, reduce the attack surface by granting Subtitle upload permissions only to non-administrator users.

Impact Analysis

This vulnerability can have severe impacts including unauthorized arbitrary file writes and reads on the server hosting Jellyfin.

An attacker can escalate privileges to administrator level and execute code remotely as the root user, potentially compromising the entire system.

Such exploitation could lead to data theft, system manipulation, service disruption, and full system compromise.

Compliance Impact

The vulnerability in Jellyfin allows arbitrary file write and remote code execution with root privileges, which can lead to unauthorized access and control over the system.

Such unauthorized access and potential data breaches could impact compliance with common standards and regulations like GDPR and HIPAA, which require protection of sensitive data and system integrity.

Exploitation requires an administrator or a user with explicit subtitle upload permissions, indicating that improper permission management could increase risk.

Fixing the vulnerability by upgrading to version 10.11.7 or restricting subtitle upload permissions can help reduce the attack surface and support compliance efforts.

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