CVE-2020-20450
📋 TL;DR
CVE-2020-20450 is a null pointer dereference vulnerability in FFmpeg 4.2's libavformat/aviobuf.c component that can cause a denial of service. Attackers can crash FFmpeg processes by providing specially crafted input files. This affects any system or application using vulnerable FFmpeg versions for media processing.
💻 Affected Systems
- FFmpeg
📦 What is this software?
Ffmpeg by Ffmpeg
⚠️ Risk & Real-World Impact
Worst Case
Complete denial of service causing FFmpeg processes to crash, potentially disrupting media processing pipelines, streaming services, or applications relying on FFmpeg for video/audio operations.
Likely Case
Application crashes when processing malicious media files, leading to service disruption and potential data loss in processing queues.
If Mitigated
Isolated crashes in sandboxed environments with proper monitoring and restart mechanisms, minimizing broader system impact.
🎯 Exploit Status
Exploitation requires providing specially crafted media files to vulnerable FFmpeg instances; trivial for attackers with file upload capabilities.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: FFmpeg 4.2.2 and later
Vendor Advisory: https://trac.ffmpeg.org/ticket/7993
Restart Required: Yes
Instructions:
1. Update FFmpeg to version 4.2.2 or later using your package manager. 2. For Debian/Ubuntu: apt update && apt upgrade ffmpeg. 3. For source installations: git pull origin release/4.2 && rebuild. 4. Restart all services using FFmpeg.
🔧 Temporary Workarounds
Input validation and sanitization
allImplement strict file validation for media uploads before passing to FFmpeg
Process isolation
linuxRun FFmpeg in isolated containers with resource limits and automatic restart
docker run --memory=512m --restart=on-failure ffmpeg-container
🧯 If You Can't Patch
- Implement strict input validation for all media files before FFmpeg processing
- Isolate FFmpeg processes in containers with resource limits and monitoring for crashes
🔍 How to Verify
Check if Vulnerable:
Check FFmpeg version: ffmpeg -version | grep 'version' and verify if it's 4.2.x (specifically 4.2.0 or 4.2.1)Check Version:
ffmpeg -version | grep 'version'Verify Fix Applied:
Confirm version is 4.2.2 or later: ffmpeg -version | grep 'version'📡 Detection & Monitoring
Log Indicators:
- Segmentation fault errors in FFmpeg logs
- Unexpected process termination of ffmpeg processes
- Core dumps in /var/crash or similar directories
Network Indicators:
- Unusual media file uploads followed by service disruption
SIEM Query:
process.name:ffmpeg AND (event.outcome:failure OR signal.name:SIGSEGV)