Jellyfin: Potential RCE via subtitle upload path traversal + .strm chain

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Summary

CVECVE-2026-35031
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-14 23:16:28 UTC
Updated2026-04-17 15:38:09 UTC
DescriptionJellyfin 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.

Risk And Classification

Primary CVSS: v3.1 9.9 CRITICAL from [email protected]

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

EPSS: 0.002710000 probability, percentile 0.506190000 (date 2026-04-20)

Problem Types: CWE-20 | CWE-22 | CWE-187 | CWE-20 CWE-20: Improper Input Validation | CWE-22 CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') | CWE-187 CWE-187: Partial String Comparison

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary9.9CRITICALCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
3.1CNADECLARED10CRITICALCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Jellyfin Jellyfin affected < 10.11.7 Not specified

References

ReferenceSourceLinkTags
github.com/jellyfin/jellyfin/releases/tag/v10.11.7 [email protected] github.com
github.com/jellyfin/jellyfin/security/advisories/GHSA-j2hf-x4q5-47j3 [email protected] github.com
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