CVE-2021-21842
📋 TL;DR
This vulnerability allows remote code execution through a specially crafted MPEG-4 video file. Attackers can exploit an integer overflow in GPAC's MPEG-4 decoder to cause heap corruption and execute arbitrary code. Users and applications that process MPEG-4 files with the vulnerable GPAC library are affected.
💻 Affected Systems
- GPAC Project on Advanced Content library
- Applications using GPAC library for MPEG-4 processing
📦 What is this software?
Gpac by Gpac
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with remote code execution, potentially leading to data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Application crash leading to denial of service, with potential for remote code execution in targeted attacks.
If Mitigated
Application crash without code execution if memory protections (ASLR, DEP) are effective.
🎯 Exploit Status
Exploitation requires user interaction to open a malicious video file. The vulnerability is well-documented with technical details available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v1.0.2 and later
Vendor Advisory: https://github.com/gpac/gpac/security/advisories/GHSA-xxxx-xxxx-xxxx
Restart Required: Yes
Instructions:
1. Update GPAC library to version 1.0.2 or later. 2. Rebuild any applications using GPAC. 3. Restart affected services or applications.
🔧 Temporary Workarounds
Disable MPEG-4 processing
allConfigure applications to disable MPEG-4 file processing if not required
Input validation
allImplement strict file type validation and size limits for video uploads
🧯 If You Can't Patch
- Implement application sandboxing to limit potential damage from exploitation
- Use memory protection mechanisms (ASLR, DEP) and monitor for crash events
🔍 How to Verify
Check if Vulnerable:
Check GPAC library version: gpac -version or check linked library version in applicationsCheck Version:
gpac -version 2>/dev/null | head -1Verify Fix Applied:
Verify GPAC version is 1.0.2 or later and test with known malicious MPEG-4 samples📡 Detection & Monitoring
Log Indicators:
- Application crashes when processing MPEG-4 files
- Memory access violation errors
- Unexpected process termination
Network Indicators:
- Unusual MPEG-4 file downloads
- Video file uploads to web applications
SIEM Query:
source="application_logs" AND ("segmentation fault" OR "access violation" OR "heap corruption") AND process="*gpac*"