CVE-2021-41459
📋 TL;DR
This vulnerability is a stack buffer overflow in MP4Box v1.0.1 that allows attackers to cause denial of service by crashing the application. It affects systems running vulnerable versions of GPAC's MP4Box multimedia processing tool. The overflow occurs when processing specially crafted XML data in the nhmldmx_send_sample() function.
💻 Affected Systems
- GPAC MP4Box
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise if combined with other vulnerabilities or memory corruption techniques.
Likely Case
Application crash causing denial of service, potentially disrupting media processing workflows.
If Mitigated
Limited to application crash with no further system impact if proper sandboxing and privilege separation are implemented.
🎯 Exploit Status
Proof of concept exists in GitHub issues. Exploitation requires feeding a specially crafted MP4 file to MP4Box.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: GPAC versions after the fix in commit 8a1b1b8
Vendor Advisory: https://github.com/gpac/gpac/issues/1912
Restart Required: No
Instructions:
1. Update GPAC to latest version from official repository. 2. Recompile MP4Box if using source. 3. Verify fix by checking version.
🔧 Temporary Workarounds
Disable NHML demuxer
allPrevent MP4Box from using the vulnerable NHML demuxer component
mp4box -no-nhml input.mp4
Input validation
allValidate and sanitize all input files before processing with MP4Box
🧯 If You Can't Patch
- Isolate MP4Box in a container or sandbox with minimal privileges
- Implement strict file upload controls and scan all media files before processing
🔍 How to Verify
Check if Vulnerable:
Check if MP4Box version is 1.0.1 or earlier, or if GPAC commit is before 8a1b1b8Check Version:
mp4box -versionVerify Fix Applied:
Test with known malicious MP4 file that triggers the overflow - application should not crash📡 Detection & Monitoring
Log Indicators:
- MP4Box crash logs
- segmentation fault errors
- core dumps from MP4Box process
Network Indicators:
- Unusual media file uploads to systems running MP4Box
SIEM Query:
process_name="mp4box" AND (event_type="crash" OR exit_code="139")