CVE-2021-21862
📋 TL;DR
This vulnerability allows remote code execution through integer truncation in GPAC's MPEG-4 decoder. Attackers can exploit it by tricking users into opening malicious video files. Systems using GPAC v1.0.1 for media processing are affected.
💻 Affected Systems
- GPAC Project on Advanced Content library
📦 What is this software?
Gpac by Gpac
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with arbitrary code execution as the user running the vulnerable software.
Likely Case
Remote code execution leading to malware installation, data theft, or system takeover.
If Mitigated
Denial of service or application crash if exploit fails or controls block execution.
🎯 Exploit Status
Exploit requires user interaction to open malicious file. Technical details and PoC available in Talos reports.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v1.0.2 or later
Vendor Advisory: https://github.com/gpac/gpac/security/advisories
Restart Required: Yes
Instructions:
1. Update GPAC to version 1.0.2 or later. 2. Rebuild any applications using GPAC library. 3. Restart affected services.
🔧 Temporary Workarounds
Disable MPEG-4 processing
allConfigure applications to disable MPEG-4/Xtra FOURCC code parsing
Application-specific configuration required
File type restrictions
allBlock .mp4 files at network perimeter or endpoint
firewall rules or endpoint policy configuration
🧯 If You Can't Patch
- Implement strict file upload controls and scanning for MP4 files
- Use application sandboxing or containerization to limit impact
🔍 How to Verify
Check if Vulnerable:
Check GPAC version: gpac -version or examine library version in applicationsCheck Version:
gpac -version 2>&1 | grep -i versionVerify Fix Applied:
Confirm GPAC version is 1.0.2 or higher📡 Detection & Monitoring
Log Indicators:
- Application crashes with memory corruption errors
- Unexpected process termination
Network Indicators:
- MP4 file downloads from untrusted sources
SIEM Query:
Process:gpac AND (EventID:1000 OR ExceptionCode:c0000005)