CVE-2021-31680
📋 TL;DR
CVE-2021-31680 is a deserialization vulnerability in YOLOv5 that allows attackers to execute arbitrary code by providing a malicious YAML configuration file. This affects any system using vulnerable versions of YOLOv5 for object detection tasks. Attackers can gain full control of affected systems through this remote code execution vulnerability.
💻 Affected Systems
- YOLOv5 (You Only Look Once version 5)
📦 What is this software?
Yolov5 by Ultralytics
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining root/administrator privileges, data exfiltration, ransomware deployment, and persistent backdoor installation.
Likely Case
Remote code execution leading to data theft, cryptocurrency mining, or use as part of a botnet for further attacks.
If Mitigated
Limited impact with proper input validation and sandboxing, potentially only denial of service if execution is prevented.
🎯 Exploit Status
Exploitation requires the attacker to provide a malicious YAML file to the vulnerable YOLOv5 instance. The vulnerability is in the PyYAML deserialization process.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Updated versions with safe YAML loading (yaml.safe_load instead of yaml.load)
Vendor Advisory: https://huntr.dev/bounties/1-other-yolov5/
Restart Required: No
Instructions:
1. Update YOLOv5 to the latest version. 2. Ensure all YAML loading uses yaml.safe_load() instead of yaml.load(). 3. Review and update any custom YAML parsing code in your implementation.
🔧 Temporary Workarounds
Use Safe YAML Loading
allReplace all instances of yaml.load() with yaml.safe_load() in the YOLOv5 codebase
sed -i 's/yaml\.load(/yaml.safe_load(/g' *.py
Input Validation
allImplement strict validation of YAML files before processing, rejecting files with suspicious content
🧯 If You Can't Patch
- Implement network segmentation to isolate YOLOv5 systems from critical infrastructure
- Use application sandboxing or containerization with minimal privileges to limit exploit impact
🔍 How to Verify
Check if Vulnerable:
Check if your YOLOv5 code uses yaml.load() instead of yaml.safe_load() for parsing configuration filesCheck Version:
Check your YOLOv5 version and review the YAML parsing implementation in utils/general.py and related filesVerify Fix Applied:
Verify that all YAML loading uses safe_load() and test with known malicious YAML files to ensure they are rejected📡 Detection & Monitoring
Log Indicators:
- Unexpected process execution from YOLOv5 context
- YAML parsing errors with suspicious content
- Unusual network connections from YOLOv5 processes
Network Indicators:
- Outbound connections to suspicious IPs from YOLOv5 systems
- Unexpected data exfiltration patterns
SIEM Query:
process_name:"python" AND (process_command_line:"yolov5" OR process_command_line:"yolo") AND (event_type:"process_execution" OR event_type:"network_connection")