CVE-2025-31499
📋 TL;DR
This vulnerability allows argument injection in Jellyfin's FFmpeg processing, which can lead to arbitrary file write and potentially remote code execution. Attackers with low-privileged user credentials can exploit this, and unauthenticated endpoints are vulnerable if a valid itemId is obtained. All Jellyfin instances before version 10.10.7 are affected.
💻 Affected Systems
- Jellyfin
📦 What is this software?
Jellyfin by Jellyfin
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, and lateral movement within the network.
Likely Case
Arbitrary file write allowing attackers to modify configuration files, install malicious plugins, or disrupt service availability.
If Mitigated
Limited impact if proper network segmentation and least privilege access controls are implemented, though file writes could still occur.
🎯 Exploit Status
Exploitation requires a valid itemId, which authenticated attackers can easily obtain. The vulnerability bypasses the previous patch for CVE-2023-49096.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 10.10.7
Vendor Advisory: https://github.com/jellyfin/jellyfin/security/advisories/GHSA-2c3c-r7gp-q32m
Restart Required: Yes
Instructions:
1. Backup your Jellyfin configuration and database. 2. Stop the Jellyfin service. 3. Update to version 10.10.7 using your package manager or manual installation. 4. Restart the Jellyfin service. 5. Verify the update was successful.
🔧 Temporary Workarounds
Network Access Restriction
allRestrict access to Jellyfin endpoints to trusted networks only
Use firewall rules to limit access to Jellyfin ports (default 8096)
Authentication Enforcement
allRequire authentication for all media streaming endpoints
Configure Jellyfin to require authentication for all users
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Jellyfin from critical systems
- Enforce multi-factor authentication and limit user privileges to minimum required
🔍 How to Verify
Check if Vulnerable:
Check Jellyfin version in web interface dashboard or via systemctl status jellyfinCheck Version:
jellyfin --version or check /usr/share/jellyfin/web/index.htmlVerify Fix Applied:
Confirm version is 10.10.7 or later in Jellyfin dashboard📡 Detection & Monitoring
Log Indicators:
- Unusual FFmpeg parameter patterns in Jellyfin logs
- Multiple failed authentication attempts followed by successful itemId enumeration
Network Indicators:
- Unusual HTTP requests to /Videos/*/stream endpoints with suspicious parameters
- Outbound connections from Jellyfin server to unexpected destinations
SIEM Query:
source="jellyfin.log" AND ("FFmpeg" AND "argument" OR "parameter")