CVE-2021-21852
📋 TL;DR
This vulnerability allows remote code execution through a heap-based buffer overflow in the GPAC library'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 leading to data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Application crash leading to denial of service, with potential for limited code execution in the context of the media processing application.
If Mitigated
Application crash without code execution if memory protections like ASLR/DEP are properly implemented and effective.
🎯 Exploit Status
Exploitation requires user interaction to open malicious file. The vulnerability is in a widely used media library making it attractive for attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v1.0.1+ (patched versions available in downstream distributions)
Vendor Advisory: https://github.com/gpac/gpac/security/advisories
Restart Required: Yes
Instructions:
1. Update GPAC library to latest version. 2. Rebuild any applications using GPAC. 3. Restart affected services/applications. 4. For Debian/Ubuntu: apt update && apt upgrade gpac
🔧 Temporary Workarounds
Disable MPEG-4 processing
allConfigure applications to disable MPEG-4 video decoding if not required
Application sandboxing
linuxRun media processing applications in restricted containers or sandboxes
docker run --security-opt no-new-privileges -it application
🧯 If You Can't Patch
- Implement strict file type validation to block untrusted MPEG-4 files
- Deploy endpoint protection with memory corruption detection capabilities
🔍 How to Verify
Check if Vulnerable:
Check GPAC library version: gpac -version | grep 'GPAC'Check Version:
gpac -version 2>/dev/null | head -1Verify Fix Applied:
Verify version is newer than v1.0.1 and check for CVE-2021-21852 in vulnerability scans📡 Detection & Monitoring
Log Indicators:
- Application crashes with segmentation faults in media processing
- Unexpected child process spawning from media applications
Network Indicators:
- Unusual outbound connections from media applications
- MPEG-4 file downloads from untrusted sources
SIEM Query:
process_name:"gpac" AND (event_type:crash OR parent_process:media_app)🔗 References
- https://talosintelligence.com/vulnerability_reports/TALOS-2021-1297
- https://www.debian.org/security/2023/dsa-5411
- https://www.talosintelligence.com/vulnerability_reports/TALOS-2021-1297
- https://talosintelligence.com/vulnerability_reports/TALOS-2021-1297
- https://www.debian.org/security/2023/dsa-5411
- https://www.talosintelligence.com/vulnerability_reports/TALOS-2021-1297
