CVE-2023-30627 – A stored cross-site scripting (XSS) vulnerabili... (How to Fix)

Q: What is the severity of CVE-2023-30627?

CVE-2023-30627 has a CVSS score of 9.0 (CRITICAL). A stored cross-site scripting (XSS) vulnerability in jellyfin-web allows attackers to make arbitrary REST API calls with admin privileges. When combined with CVE-2023-30626, this can lead to remote code execution on the Jellyfin server. All Jellyfin instances running versions 10.1.0 through 10.8.9 are affected.

📋 TL;DR

A stored cross-site scripting (XSS) vulnerability in jellyfin-web allows attackers to make arbitrary REST API calls with admin privileges. When combined with CVE-2023-30626, this can lead to remote code execution on the Jellyfin server. All Jellyfin instances running versions 10.1.0 through 10.8.9 are affected.

💻 Affected Systems

Products:

jellyfin-web
Jellyfin

Versions: 10.1.0 through 10.8.9

Operating Systems: All platforms running Jellyfin

Default Config Vulnerable: ⚠️ Yes

Notes: This affects the web client component of Jellyfin media servers.

📦 What is this software?

Jellyfin by Jellyfin

View all CVEs affecting Jellyfin →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution with the privileges of the Jellyfin service account, potentially leading to complete system compromise, data theft, or ransomware deployment.

🟠

Likely Case

Unauthorized administrative actions, data exfiltration, or lateral movement within the network.

🟢

If Mitigated

Limited impact if proper network segmentation, least privilege service accounts, and web application firewalls are in place.

🌐 Internet-Facing: HIGH

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires XSS payload delivery and combination with CVE-2023-30626 for RCE.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 10.8.10

Vendor Advisory: https://github.com/jellyfin/jellyfin-web/security/advisories/GHSA-89hp-h43h-r5pq

Restart Required: Yes

Instructions:

1. Stop Jellyfin service. 2. Update to version 10.8.10 or later via package manager or manual installation. 3. Restart Jellyfin service.

🔧 Temporary Workarounds

No official workarounds

all

The vendor states there are no known workarounds for this vulnerability.

🧯 If You Can't Patch

Isolate Jellyfin server from internet and restrict network access to trusted users only.
Implement strict Content Security Policy (CSP) headers and web application firewall rules.

🔍 How to Verify

Check if Vulnerable:

Check Jellyfin web interface version in settings or run: jellyfin --version

Check Version:

jellyfin --version

Verify Fix Applied:

Confirm version is 10.8.10 or higher and test XSS payloads no longer execute.

📡 Detection & Monitoring

Log Indicators:

Unusual REST API calls with admin privileges
Suspicious JavaScript execution in device.js context

Network Indicators:

Unexpected outbound connections from Jellyfin server
Unusual API request patterns

SIEM Query:

source="jellyfin" AND (event="admin_api_call" OR event="xss_attempt")

📊 Metadata

CVE ID: CVE-2023-30627

CVSS v3 Score: 9.0 (CRITICAL)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

CWE: CWE-79

Published: April 24, 2023

Last Updated: November 21, 2024

🔗 References

https://github.com/jellyfin/jellyfin-web/commit/b88a5951e1a517ff4c820e693d9c0da981cf68ee Patch
https://github.com/jellyfin/jellyfin-web/releases/tag/v10.8.10 Release Notes
https://github.com/jellyfin/jellyfin-web/security/advisories/GHSA-89hp-h43h-r5pq Vendor Advisory
https://github.com/jellyfin/jellyfin/security/advisories/GHSA-9p5f-5x8v-x65m Exploit,Patch,Vendor Advisory
https://github.com/jellyfin/jellyfin-web/commit/b88a5951e1a517ff4c820e693d9c0da981cf68ee Patch
https://github.com/jellyfin/jellyfin-web/releases/tag/v10.8.10 Release Notes
https://github.com/jellyfin/jellyfin-web/security/advisories/GHSA-89hp-h43h-r5pq Vendor Advisory
https://github.com/jellyfin/jellyfin/security/advisories/GHSA-9p5f-5x8v-x65m Exploit,Patch,Vendor Advisory

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