CVE-2021-33499
📋 TL;DR
This vulnerability in Pexip Infinity allows remote attackers to cause denial of service by sending specially crafted H.264 video input without proper validation. It affects all Pexip Infinity deployments before version 26 that process video streams.
💻 Affected Systems
- Pexip Infinity
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete service disruption making the Pexip Infinity platform unavailable for all users, potentially requiring system restart or reconfiguration.
Likely Case
Service instability, dropped calls, or degraded video quality affecting user experience during video conferences.
If Mitigated
Minimal impact with proper network segmentation and input validation controls in place.
🎯 Exploit Status
The vulnerability requires sending malformed H.264 video streams, which can be done by any client or attacker with network access to the system.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version 26 or later
Vendor Advisory: https://docs.pexip.com/admin/security_bulletins.htm
Restart Required: Yes
Instructions:
1. Backup current configuration. 2. Upgrade to Pexip Infinity version 26 or later. 3. Restart the system. 4. Verify the upgrade was successful.
🔧 Temporary Workarounds
Network segmentation
allRestrict access to Pexip Infinity systems to trusted networks only
Input validation proxy
allDeploy a proxy that validates H.264 streams before they reach Pexip Infinity
🧯 If You Can't Patch
- Implement strict network access controls to limit who can send video streams to the system
- Monitor system performance and logs for signs of DoS attacks and have incident response procedures ready
🔍 How to Verify
Check if Vulnerable:
Check the Pexip Infinity version via the admin web interface or SSH to the appliance and run 'pexip --version'Check Version:
pexip --versionVerify Fix Applied:
Confirm version is 26 or higher and test video conferencing functionality with various H.264 streams📡 Detection & Monitoring
Log Indicators:
- Unusual system crashes
- High CPU/memory usage spikes
- Failed video processing errors
- Service restart events
Network Indicators:
- Unusual volume of H.264 traffic from single sources
- Malformed video packet patterns
- Connection floods to video ports
SIEM Query:
source="pexip" AND (event_type="crash" OR event_type="restart" OR error_message="H.264" OR cpu_usage>90)