Jellyfin up to 10.11.6 Subtitle Upload Endpoint Subtitles Format input validation

CVSS Meta Temp Score
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CTI Interest Score
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7.9$0-$5k0.81

Summaryinfo

A vulnerability labeled as critical has been found in Jellyfin up to 10.11.6. This affects an unknown part of the file /Videos/{itemId}/Subtitles of the component Subtitle Upload Endpoint. The manipulation of the argument Format results in input validation. This vulnerability is reported as CVE-2026-35031. The attack can be launched remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Jellyfin up to 10.11.6. It has been classified as critical. Affected is an unknown part of the file /Videos/{itemId}/Subtitles of the component Subtitle Upload Endpoint. The manipulation of the argument Format with an unknown input leads to a input validation vulnerability. CWE is classifying the issue as 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. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-35031 since 03/31/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. There are known technical details, but no exploit is available.

Upgrading to version 10.11.7 eliminates this vulnerability. The upgrade is hosted for download at github.com.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.1
VulDB Meta Temp Score: 7.9

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 9.9
CNA Vector (GitHub_M): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Input validation
CWE: CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Jellyfin 10.11.7

Timelineinfo

03/31/2026 CVE reserved
04/15/2026 +15 days Advisory disclosed
04/15/2026 +0 days VulDB entry created
04/15/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-j2hf-x4q5-47j3
Status: Confirmed

CVE: CVE-2026-35031 (🔒)
GCVE (CVE): GCVE-0-2026-35031
GCVE (VulDB): GCVE-100-357612

Entryinfo

Created: 04/15/2026 06:49
Changes: 04/15/2026 06:49 (66)
Complete: 🔍
Cache ID: 216::103

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