Cross-Site Scripting (XSS) in Jellyfin (CVE-2026-49220)
Summary
Cross-site scripting in Jellyfin (CVE-2026-49220). Confidential information can be exposed externally. Mitigation: upgrade to 10.11.9 or later.
Original description
The description as published by the source.
Jellyfin is an open source self hosted media server. Prior to 10.11.9, a potential XSS attack exists in Jellyfin which can allow a non-privileged user to execute arbitrary Javascript in the context of a logged-in Administrative user, resulting in numerous potential issues. The Client header during an AuthenticateByName can contain arbitrary HTML and Javascript, which will then be executed by the Administrative user when visiting the Access tab of the user in question from within the dashboard. This vulnerability is fixed in 10.11.9.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-49220 has been found in Jellyfin.
Confidential information can be exposed externally. CVSS score: 5.7/10.
What to do: upgrade Jellyfin to 10.11.9 or later.
If unsure, ask your IT team or search "Jellyfin CVE-2026-49220" on the vendor's site.
CVE-2026-49220 (Jellyfin) — CWE-79 / CVSS v3 5.7
Attack vector: remote (network-reachable)
Patched: 10.11.9 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Cross-site scripting (XSS) (CWE-79) exists in Jellyfin.
Check the vendor advisory for the affected versions of Jellyfin.
Severity: Medium (CVSS 5.7/10). Confidential information can be exposed externally.
Update to 10.11.9.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Jellyfin' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'Jellyfin' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
Jellyfinを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade Jellyfin to 10.11.9ステージング環境で 10.11.9 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov