CVE-2025-39401: mojoomla WPAMS RCE Vulnerability

CVE-2025-39401 Overview

CVE-2025-39401 is an Unrestricted Upload of File with Dangerous Type vulnerability affecting the mojoomla WPAMS (WordPress Apartment Management System) plugin. This vulnerability allows remote attackers to upload malicious web shells to the web server without any authentication, potentially leading to complete server compromise. The vulnerability stems from inadequate file type validation in the plugin's upload functionality.

Critical Impact

This vulnerability enables unauthenticated attackers to upload arbitrary files including web shells, potentially resulting in complete server takeover, data theft, and lateral movement within the hosting environment.

Affected Products

• WPAMS (WordPress Apartment Management System) plugin versions through 44.0 (17-08-2023)
• WordPress installations running vulnerable WPAMS versions

Discovery Timeline

• 2025-05-19 - CVE CVE-2025-39401 published to NVD
• 2025-05-21 - Last updated in NVD database

Technical Details for CVE-2025-39401

Vulnerability Analysis

This vulnerability falls under CWE-434 (Unrestricted Upload of File with Dangerous Type), which occurs when a web application allows users to upload files without properly validating the file type, content, or extension. In the case of WPAMS, the plugin fails to implement adequate security controls on file upload endpoints, allowing attackers to bypass any existing restrictions and upload executable code to the server.

The network-accessible nature of this vulnerability means attackers can exploit it remotely without requiring any prior authentication or user interaction. When successfully exploited, the attacker gains the ability to execute arbitrary code on the web server with the privileges of the web server process.

Root Cause

The root cause of this vulnerability lies in the WPAMS plugin's failure to properly validate uploaded files. The plugin does not implement sufficient checks to verify that uploaded files are of an expected and safe type. This may include missing or bypassable extension validation, lack of MIME type verification, absence of content inspection, or insufficient server-side restrictions on file execution in upload directories.

Attack Vector

The attack vector for this vulnerability is network-based, requiring no authentication, no user interaction, and involving low attack complexity. An attacker can exploit this vulnerability by sending crafted HTTP requests to the vulnerable file upload endpoint, uploading a malicious PHP web shell disguised or presented in a way that bypasses any weak validation.

Once the web shell is uploaded to the server, the attacker can access it via a direct URL request, gaining interactive command execution capabilities on the target system. This can lead to data exfiltration, installation of backdoors, privilege escalation, and lateral movement across the network.

Detection Methods for CVE-2025-39401

Indicators of Compromise

• Unexpected PHP files or files with unusual extensions in WordPress upload directories, particularly within WPAMS-related folders
• Web server logs showing POST requests to WPAMS upload endpoints from unknown or suspicious IP addresses
• New or modified files in wp-content/uploads/ or plugin-specific directories with executable content
• Outbound network connections from the web server process to unknown external destinations

Detection Strategies

• Monitor file system changes in WordPress upload directories using file integrity monitoring (FIM) tools
• Analyze web server access logs for suspicious POST requests targeting WPAMS plugin endpoints
• Deploy web application firewalls (WAF) with rules to detect and block web shell upload attempts
• Implement endpoint detection and response (EDR) solutions to identify malicious file creation and command execution

Monitoring Recommendations

• Enable verbose logging on WordPress and the web server to capture all upload-related activity
• Configure alerts for new file creation events in plugin directories with executable extensions (.php, .phtml, .phar)
• Monitor for unusual process spawning from web server processes (e.g., php, apache, nginx spawning shells)
• Review server logs regularly for indicators of post-exploitation activity such as reconnaissance commands

How to Mitigate CVE-2025-39401

Immediate Actions Required

• Immediately deactivate and remove the WPAMS plugin from affected WordPress installations until a patched version is available
• Audit upload directories for any suspicious or recently created files, particularly PHP files
• Review web server access logs for evidence of exploitation attempts or successful compromises
• Consider temporarily blocking access to the affected upload endpoints at the web server or WAF level

Patch Information

As of the last NVD update on 2025-05-21, the vulnerability affects WPAMS versions through 44.0 (17-08-2023). Users should monitor the Patchstack WordPress Vulnerability Report for updates on patched versions and remediation guidance from the vendor.

Workarounds

• Remove or disable the WPAMS plugin until an official patch is released
• Implement web application firewall (WAF) rules to block suspicious file uploads and web shell signatures
• Restrict file upload directories to disallow script execution via web server configuration (e.g., using .htaccess for Apache)
• Apply network-level access controls to limit access to WordPress admin areas and plugin endpoints

# Apache .htaccess configuration to prevent PHP execution in uploads directory
# Place this in wp-content/uploads/.htaccess

<FilesMatch "\.(?:php|phtml|phar|php[0-9])$">
    Require all denied
</FilesMatch>

# Alternatively, disable script handlers entirely
<IfModule mod_php.c>
    php_flag engine off
</IfModule>