Jellyfin EUVD-2026-22766

Requires authenticated access to Jellyfin versions prior to 10.11.7. Attacker must be any authenticated user (EnableLiveTvManagement permission defaults to true). Exploit targets POST /LiveTv/TunerHosts endpoint with unvalidated tuner URLs for SSRF and local file read via non-HTTP paths.

Real-world risk is substantial due to convergence of multiple high-risk factors. CVSS 4.0 vector (AV:N/AC:L/PR:L) indicates network-accessible exploitation with low complexity requiring only standard user credentials. The vulnerability is highly automatable given the straightforward API abuse pattern: any authenticated user can POST to the tuner endpoint without additional authorization checks. Technical impact is severe (VC:H/VI:H) with high confidentiality and integrity impact in the vulnerable system, plus low subsequent system impact (SC:L/SI:L) from privilege escalation. While no CISA KEV listing or public exploit code (POC) confirmed at analysis time, the detailed GitHub Security Advisory (GHSA-8fw7-f233-ffr8) publicly discloses the complete attack chain, significantly lowering the skill barrier for exploitation. The default-enabled permission creates a broad attack surface across all Jellyfin instances with standard user accounts. SSVC decision factors: exploitation status is publicly disclosed with technical details; automatable with simple scripting; technical impact enables admin takeover. This is a genuine priority requiring immediate patching despite absence of confirmed exploitation, particularly for internet-facing Jellyfin instances with user account registrations enabled.

An attacker creates a standard user account on an internet-accessible Jellyfin instance (or uses compromised credentials). Leveraging the default-enabled EnableLiveTvManagement permission, they POST to /LiveTv/TunerHosts adding an M3U tuner with URL pointing to their controlled web server. The attacker's server responds with a crafted M3U playlist containing a channel entry referencing file:///var/lib/jellyfin/data/jellyfin.db (typical database path). When Jellyfin parses this M3U, it reads the local database file and transmits contents back to the attacker's server. The attacker extracts administrator session tokens from the exfiltrated database, uses these tokens to authenticate as admin, and achieves full system control including ability to execute server-side tasks, modify configurations, or pivot to underlying host system.