CVE-2022-31505
📋 TL;DR
This vulnerability allows attackers to perform absolute path traversal attacks in the cheo0/MercadoEnLineaBack repository. By exploiting unsafe usage of Flask's send_file function, attackers can access arbitrary files on the server. This affects any system running this vulnerable GitHub repository code.
💻 Affected Systems
- cheo0/MercadoEnLineaBack repository
📦 What is this software?
Mercadoenlineaback by Mercadoenlineaback Project
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise including sensitive file disclosure (config files, credentials, database files), potential remote code execution, and data exfiltration.
Likely Case
Unauthorized access to sensitive server files including configuration files, source code, and potentially user data stored on the filesystem.
If Mitigated
Limited file access restricted by proper input validation and path sanitization, with minimal impact to system integrity.
🎯 Exploit Status
Path traversal vulnerabilities are well-understood and easily exploitable with simple HTTP requests.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 2022-05-04
Vendor Advisory: https://github.com/github/securitylab/issues/669
Restart Required: Yes
Instructions:
1. Update to the latest version of the repository
2. Ensure all path inputs are properly validated and sanitized
3. Restart the Flask application
🔧 Temporary Workarounds
Input Validation Middleware
allAdd middleware to validate and sanitize all file path inputs before processing
# Add input validation in Flask routes
from werkzeug.utils import safe_join
import os
# Replace unsafe send_file usage with:
def safe_send_file(path):
safe_path = safe_join('/allowed/base/path', path)
if safe_path is None or not os.path.exists(safe_path):
return 'File not found', 404
return send_file(safe_path)
🧯 If You Can't Patch
- Implement strict input validation for all file path parameters
- Deploy web application firewall (WAF) with path traversal protection rules
🔍 How to Verify
Check if Vulnerable:
Review Flask route handlers for unsafe send_file usage with user-controlled inputCheck Version:
Check repository commit date or version metadataVerify Fix Applied:
Test path traversal attempts (e.g., '../../etc/passwd') and verify they are blocked📡 Detection & Monitoring
Log Indicators:
- Multiple 404 errors for unusual file paths
- Requests containing '../' patterns in URLs
- Access to sensitive system files
Network Indicators:
- HTTP requests with path traversal sequences in parameters
- Unusual file access patterns from single IP
SIEM Query:
source="web_logs" AND (url="*../*" OR url="*..\\*" OR status=404 AND url="*/etc/*" OR url="*/windows/*")