CVE-2026-49246
LowCVSS 1.7Exploitation Probability (EPSS)
Low risk17th percentile — higher than 17% of all known CVEs
Summary
Jellyfin prior to version 10.11.10 has a vulnerability that allows a specially crafted MKV file with forged filename tags to exploit missing path sanitization during playback. As a result, a malicious MKV file can redirect attachment extraction to any absolute path on disk.
Risk Assessment
Exploitation of this vulnerability may lead to unauthorized access to files on the server, posing a serious threat to the organization's data security.
Recommendation
It is recommended to update Jellyfin to version 10.11.10 or later to mitigate this vulnerability and to implement additional security measures to monitor and control MKV file playback.
Original NVD description (English source)
Jellyfin is an open source self hosted media server. Prior to 10.11.10, a specifically crafted MKV file containing forged filename tags can be leveraged to exploit missing path sanitization during playback. Jellyfin treats the MKV file name tag on MKV attachments as trusted and passes it unsanitized into Path.Combine(attachmentFolder, fileName) inside PathManager.GetAttachmentPath. Because .NET's Path.Combine neither normalises .. nor rejects a rooted second argument, a crafted MKV can redirect Jellyfin's MKV attachment extraction to any absolute path on disk. This triggers on any playback action of the affected video on a client which will attempt to burn in the subtitles by default.g This vulnerability is fixed in 10.11.10.