CVE-2026-49247 — HIGH (8.8)

Vulnerability Description

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.

CVSS Score

8.8

HIGH

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

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

HIGH

Integrity

HIGH

Availability

HIGH

Related Weaknesses (CWE)

CWE-22

References

https://github.com/jellyfin/jellyfin/security/advisories/GHSA-jg92-mrxq-vv75

FAQ

What is CVE-2026-49247?

CVE-2026-49247 is a vulnerability with a CVSS score of 8.8 (HIGH). 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 unsani...

How severe is CVE-2026-49247?

CVE-2026-49247 has been rated HIGH with a CVSS base score of 8.8/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-49247?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.