CVE-2023-26686
📋 TL;DR
CVE-2023-26686 is a critical file upload vulnerability in CS-Cart MultiVendor 4.16.1 that allows remote attackers to upload malicious files through the image upload feature when customizing a shop. This can lead to arbitrary code execution on the server. All users running CS-Cart MultiVendor 4.16.1 are affected.
💻 Affected Systems
- CS-Cart MultiVendor
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise allowing attackers to execute arbitrary code, steal data, install backdoors, and pivot to other systems.
Likely Case
Attackers upload web shells to gain persistent access, deface websites, or steal sensitive customer and vendor data.
If Mitigated
If proper file type validation and upload restrictions are in place, attackers cannot upload executable files, limiting impact to denial of service or storage consumption.
🎯 Exploit Status
Exploitation requires access to shop customization interface. Public proof-of-concept demonstrates file upload bypass.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.16.2 or later
Vendor Advisory: https://www.cs-cart.com/multivendor.html
Restart Required: No
Instructions:
1. Backup your CS-Cart installation and database. 2. Update to CS-Cart MultiVendor 4.16.2 or later through the admin panel or manual installation. 3. Verify the update completed successfully.
🔧 Temporary Workarounds
Restrict file upload extensions
allConfigure web server to block upload of executable file types
# For Apache: Add to .htaccess
<FilesMatch "\.(php|phtml|php3|php4|php5|php7|phar|pl|py|jsp|asp|aspx|sh|cgi|exe|dll)">
Order Allow,Deny
Deny from all
</FilesMatch>
# For Nginx: Add to server block
location ~* \.(php|phtml|php3|php4|php5|php7|phar|pl|py|jsp|asp|aspx|sh|cgi|exe|dll)$ {
deny all;
}
Disable shop customization
allTemporarily disable shop customization features until patched
# Modify CS-Cart configuration or disable relevant modules in admin panel
🧯 If You Can't Patch
- Implement strict file upload validation in application code to only allow specific image file types.
- Use a Web Application Firewall (WAF) to block malicious file upload attempts.
🔍 How to Verify
Check if Vulnerable:
Check if running CS-Cart MultiVendor 4.16.1. Attempt to upload a non-image file through shop customization image upload feature.Check Version:
# Check CS-Cart version in admin panel or config.php fileVerify Fix Applied:
Verify version is 4.16.2 or later. Test that only allowed image file types can be uploaded through shop customization.📡 Detection & Monitoring
Log Indicators:
- Unusual file uploads to shop customization endpoints
- Uploads of non-image file types with executable extensions
- Multiple failed upload attempts
Network Indicators:
- POST requests to image upload endpoints with unusual file types
- Traffic patterns indicating file upload exploitation
SIEM Query:
source="web_server" AND (uri_path="*/image_upload*" OR uri_path="*/file_upload*") AND (file_extension="php" OR file_extension="jsp" OR file_extension="asp" OR file_extension="exe")