CVE-2026-31852: Jellyfin Improper Privilege Management (CVSS 10)

Jellyfin is an open source self hosted media server. Versions prior to 10.11.7 contain an unauthenticated arbitrary file read vulnerability via ffmpeg argument injection through the StreamOptions query parameter parsing mechanism. The ParseStreamOptions method in StreamingHelpers.cs adds any lowercase query parameter to a dictionary without validation, bypassing the RegularExpression attribute on the level controller parameter, and the unsanitized value is concatenated directly into the ffmpeg command line. By injecting a drawtext filter with a textfile argument, an attacker can read arbitrary server files such as /etc/shadow and exfiltrate their contents as text rendered in the video stream response. The vulnerable /Videos/{itemId}/stream endpoint has no Authorize attribute, making this exploitable without authentication, though item GUIDs are pseudorandom and require an authenticated user to obtain. This issue has been fixed in version 10.11.7.

Jellyfin is an open source self hosted media server. Versions prior to 10.11.7 contain a vulnerability chain in the LiveTV M3U tuner endpoint (POST /LiveTv/TunerHosts), where the tuner URL is not validated, allowing local file read via non-HTTP paths and Server-Side Request Forgery (SSRF) via HTTP URLs. This is exploitable by any authenticated user because the EnableLiveTvManagement permission defaults to true for all new users. An attacker can chain these vulnerabilities by adding an M3U tuner pointing to an attacker-controlled server, serving a crafted M3U with a channel pointing to the Jellyfin database, exfiltrating the database to extract admin session tokens, and escalating to admin privileges. This issue has been fixed in version 10.11.7. If users are unable to upgrade immediately, they can disable Live TV Management privileges for all users.

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.

In MicroXR Blobstore, there is a possible way to access other app's files due to a missing permission check. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. In versions 2.61.2 and below, any unauthenticated visitor can register a full administrator account when self-registration (signup = true) is enabled and the default user permissions have perm.admin = true. The signup handler blindly applies all default settings (including Perm.Admin) to the new user without any server-side guard that strips admin from self-registered accounts. The signupHandler is supposed to create unprivileged accounts for new visitors. It contains no explicit user.Perm.Admin = false reset after applying defaults. If an administrator (intentionally or accidentally) configures defaults.perm.admin = true and also enables signup, every account created via the public registration endpoint is an administrator with full control over all files, users, and server settings. This issue has been resolved in version 2.62.0.

The vulnerability exists in BLUVOYIX due to improper authentication in the BLUVOYIX admin APIs. An unauthenticated remote attacker could exploit this vulnerability by sending specially crafted HTTP requests to the vulnerable admin API to create a new user with admin privileges. Successful exploitation of this vulnerability could allow the attacker to gain full access to customers' data and completely compromise the targeted platform by logging in to the newly-created admin user.