Quick answers
- Is CVE-2026-49220 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-49220 being exploited in the wild.
- How severe is CVE-2026-49220?
- Medium severity, with a CVSS score of 5.7, published 24 June 2026.
- Which products and versions are affected?
- Jellyfin < 10.11.9.
- Is there a fix for CVE-2026-49220?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-49220 attacked?
- It is attacked over the network, in a network appliance.
- Am I affected by CVE-2026-49220?
- Check whether you run Jellyfin at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A stored Cross-Site Scripting (XSS) vulnerability exists in Jellyfin due to improper sanitization of the 'Client' header during the 'AuthenticateByName' process. An authenticated, non-privileged attacker can supply a malicious payload within this header. The payload is subsequently executed in the browser of an administrative user when they navigate to the 'Access' tab of the attacker's account within the dashboard. This allows for arbitrary JavaScript execution in the context of the administrator's session, which could lead to unauthorized data access. The issue is resolved in version 10.11.9 by implementing improved sanitization of the Client header.
Affected products
- Jellyfin Jellyfin < 10.11.9
Timeline
- 2026-06-10: advisory: GitHub Security Advisory published
- 2026-06-24: disclosed: NVD publication date