CVE-2020-37073: Victor CMS 1.0 RCE Vulnerability

CVE-2020-37073 Overview

CVE-2020-37073 is an authenticated arbitrary file upload vulnerability affecting Victor CMS 1.0. The vulnerability allows administrators to upload PHP files with arbitrary content through the user_image parameter. Attackers can exploit this flaw to upload a malicious PHP shell to the /img/ directory and subsequently execute system commands by accessing the uploaded file with a cmd parameter.

Critical Impact

Successful exploitation enables remote code execution on the underlying server, potentially allowing complete system compromise through an authenticated administrative session.

Affected Products

• Victor CMS 1.0

Discovery Timeline

• 2026-02-03 - CVE CVE-2020-37073 published to NVD
• 2026-02-04 - Last updated in NVD database

Technical Details for CVE-2020-37073

Vulnerability Analysis

This vulnerability is classified as CWE-434 (Unrestricted Upload of File with Dangerous Type). The flaw exists in Victor CMS 1.0's file upload functionality, which fails to properly validate the type and content of files uploaded through the user_image parameter. The application accepts PHP files without adequate restrictions, allowing authenticated administrators to upload executable server-side scripts.

The vulnerability requires administrative authentication to exploit, which limits the initial attack surface. However, once an attacker gains access to an administrative account—whether through credential theft, brute force, or social engineering—they can leverage this file upload weakness to achieve full remote code execution on the web server.

Root Cause

The root cause of this vulnerability lies in insufficient input validation and lack of file type restrictions in the user image upload functionality. The application fails to implement proper checks on:

1. File extension validation - allowing .php extensions instead of restricting to image types
2. MIME type verification - not validating that the uploaded content matches expected image formats
3. Content inspection - not scanning file contents for executable code

This combination of missing security controls allows arbitrary PHP code to be written to the web-accessible /img/ directory.

Attack Vector

The attack is network-based and requires an authenticated administrative session. An attacker would craft a malicious PHP file containing a web shell and upload it through the vulnerable user_image parameter. Once uploaded, the attacker can access the file directly via the /img/ directory and pass system commands through the cmd parameter.

The exploitation flow involves uploading a PHP shell that reads and executes commands from user input, enabling the attacker to run arbitrary system commands with the privileges of the web server process. Technical details and proof-of-concept code are available in the Exploit-DB #48490 entry and the VulnCheck Security Advisory.

Detection Methods for CVE-2020-37073

Indicators of Compromise

• Unexpected PHP files in the /img/ directory that were not part of the original CMS installation
• Web server access logs showing requests to files in /img/ with cmd parameters
• Process execution anomalies originating from the web server process (e.g., www-data or apache spawning shell processes)

Detection Strategies

• Monitor file system changes in web-accessible directories, particularly /img/, for new PHP file creation
• Implement web application firewall (WAF) rules to detect and block requests containing shell command parameters
• Review web server access logs for suspicious patterns such as requests to image directories with query string parameters

Monitoring Recommendations

• Enable file integrity monitoring (FIM) on the Victor CMS installation directory
• Configure alerts for any new executable file uploads in the /img/ directory
• Monitor outbound network connections from the web server for potential reverse shell activity

How to Mitigate CVE-2020-37073

Immediate Actions Required

• Restrict file upload functionality to accept only validated image file types (JPEG, PNG, GIF)
• Implement server-side MIME type validation and content inspection for all uploaded files
• Consider removing or disabling Victor CMS 1.0 until a patched version is available
• Review administrative accounts for unauthorized access and enforce strong authentication policies

Patch Information

No official vendor patch information is currently available for this vulnerability. Organizations using Victor CMS 1.0 should consult the GitHub repository for any updates and the VulnCheck Security Advisory for additional guidance.

Workarounds

• Configure the web server to disable PHP execution within the /img/ directory using .htaccess or server configuration
• Implement a whitelist-based file extension filter that only permits known image extensions
• Move uploaded files outside the web root or to a non-executable storage location
• Deploy a web application firewall with rules to block file upload attacks

# Apache configuration to disable PHP execution in /img/ directory
# Add to .htaccess in the /img/ directory or virtual host configuration
<Directory "/var/www/html/img">
    php_admin_flag engine off
    RemoveHandler .php .phtml .php3 .php4 .php5 .phps
    AddType text/plain .php .phtml .php3 .php4 .php5 .phps
</Directory>