The vulnerability allows an attacker to inject malicious arguments into the ffmpeg command line through the StreamOptions query parameter, enabling arbitrary read of server files such as /etc/shadow. Because the payload is rendered as text in the video stream response, an attacker can exfiltrate sensitive data without needing to capture the stream output separately. The flaw is a consequence of missing authorization checks and unsanitized input handling, making it a severe confidentiality breach.

The affected product is Jellyfin, the open-source media server. Versions before 10.11.7 are vulnerable; the issue was corrected in release 10.11.7. The exploit relies on the /Videos/{itemId}/stream endpoint, which lacks an Authorize attribute and accepts any lowercase query parameter without validation. Users who can obtain item GUIDs (typically authenticated) can use them to target specific media items.

The CVSS base score is 9.3, indicating critical severity. EPSS is not available, so current exploitation probability cannot be quantified. The vulnerability is not listed in CISA's KEV catalog. Attackers can reach the vulnerable endpoint over the network, assuming the server is exposed. Since the endpoint accepts arbitrary query parameters, an unauthenticated attacker can craft requests to read arbitrary files by embedding a drawtext filter that references a textfile argument. The absence of authentication for the stream endpoint makes exploitation possible without needing user credentials, though obtaining GUIDs still requires authentication. The risk is therefore high, pending the availability of a patch or mitigation.