Componentpedia / Listings / Jellyfin.Model / 10.8.3

Jellyfin is a Free Software Media System for managing and streaming media. In affected versions there is an argument injection in the VideosController, specifically the /Videos/<itemId>/stream and /Videos/<itemId>/stream.<container> endpoints which are present in the current Jellyfin version. Additional endpoints in the AudioController might also be vulnerable, as they differ only slightly in execution. Those endpoints are reachable by an unauthenticated user. In order to exploit this vulnerability an unauthenticated attacker has to guess an itemId, which is a completely random GUID. It’s a very unlikely case even for a large media database with lots of items. Without an additional information leak, this vulnerability shouldn’t be directly exploitable, even if the instance is reachable from the Internet. There are a lot of query parameters that get accepted by the method. At least two of those, videoCodec and audioCodec are vulnerable to the argument injection. The values can be traced through a lot of code and might be changed in the process. However, the fallback is to always use them as-is, which means we can inject our own arguments. Those arguments land in the command line of FFmpeg. Because UseShellExecute is always set to false, we can’t simply terminate the FFmpeg command and execute our own. It should only be possible to add additional arguments to FFmpeg, which is powerful enough as it stands. There is probably a way of overwriting an arbitrary file with malicious content. This vulnerability has been addressed in version 10.8.13. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Jellyfin is a system for managing and streaming media. Prior to version 10.8.13, the /System/MediaEncoder/Path endpoint executes an arbitrary file using ProcessStartInfo via the ValidateVersion function. A malicious administrator can setup a network share and supply a UNC path to /System/MediaEncoder/Path which points to an executable on the network share, causing Jellyfin server to run the executable in the local context. The endpoint was removed in version 10.8.13.

Previous versions of Jellyfin were vulnerable to argument injection in FFmpeg. This can be leveraged to possibly achieve remote code execution by anyone with credentials to a low-privileged user. This vulnerability was previously reported in GHSA-866x-wj5j-2vf4 and patched in 10.8.13, but that patch can be bypassed. The original fix sanitizes some parameters to make injection impossible, but certain unsanitized parameters can still be used for argument injection. The same unauthenticated endpoints are vulnerable: /Videos/<itemId>/stream and /Videos/<itemId>/stream.<container>, likely alongside similar endpoints in AudioController. As reported by @mawalu and @FredericLinn in the previous advisory, this argument injection can be exploited to achieve arbitrary file write, leading to possible remote code execution through the plugin system. To restate from their report, this is a vulnerability in unauthenticated endpoints, however a valid itemId is required for exploitation which isn't directly accessible for unauthenticated attackers. Any authenticated attacker could easily retrieve a valid itemId, though, which is all the information needed to exploit this vulnerability.

Jellyfin is an open source self hosted media server. The Jellyfin user profile image upload accepts SVG files, allowing for a stored XSS attack against an admin user via a specially crafted malicious SVG file. When viewed by an admin outside of the Jellyfin Web UI (e.g. via "view image" in a browser), this malicious SVG file could interact with the browser's LocalStorage and retrieve an AccessToken, which in turn can be used in an API call to elevate the target user to a Jellyfin administrator. The actual attack vector is unlikely to be exploited, as it requires specific actions by the administrator to view the SVG image outside of Jellyfin's WebUI, i.e. it is not a passive attack. The underlying exploit mechanism is solved by PR #12490, which forces attached images (including the potential malicious SVG) to be treated as attachments and thus downloaded by browsers, rather than viewed. This prevents exploitation of the LocalStorage of the browser. This PR has been merged and the relevant code changes are included in release version 10.9.10. All users are advised to upgrade.