CVE-2025-26916: Massive Dynamic RCE Vulnerability

CVE-2025-26916 Overview

CVE-2025-26916 is a critical PHP Remote File Inclusion (RFI) vulnerability affecting the EPC Massive Dynamic WordPress theme. This vulnerability stems from improper control of filename for include/require statements in PHP programs (CWE-98), allowing unauthenticated attackers to include arbitrary files from remote or local sources.

The vulnerability enables attackers to execute arbitrary PHP code on the target server without authentication, potentially leading to complete site compromise, data exfiltration, and server takeover.

Critical Impact

Unauthenticated remote attackers can exploit this PHP file inclusion vulnerability to execute arbitrary code, potentially gaining complete control over WordPress installations running vulnerable versions of the Massive Dynamic theme.

Affected Products

• EPC Massive Dynamic WordPress Theme through version 8.2
• WordPress installations using Massive Dynamic theme versions n/a through 8.2

Discovery Timeline

• 2025-03-10 - CVE-2025-26916 published to NVD
• 2025-03-10 - Last updated in NVD database

Technical Details for CVE-2025-26916

Vulnerability Analysis

This vulnerability is classified as Improper Control of Filename for Include/Require Statement in PHP Program, commonly known as PHP Remote File Inclusion (RFI) or Local File Inclusion (LFI). The flaw exists in the Massive Dynamic WordPress theme, where user-controllable input is passed to PHP's include(), require(), or similar file inclusion functions without proper validation or sanitization.

The vulnerability can be exploited remotely over a network connection, though exploitation requires high attack complexity. Despite this complexity barrier, successful exploitation requires no authentication or user interaction, and the impact extends beyond the vulnerable component's security scope—potentially affecting the underlying server and other hosted applications.

Root Cause

The root cause lies in insufficient input validation when processing file paths in the Massive Dynamic theme. The theme fails to properly sanitize user-supplied input before passing it to PHP file inclusion functions. This allows attackers to manipulate the file path parameter to include arbitrary local files (LFI) or potentially remote files (RFI) if PHP's allow_url_include directive is enabled.

Common patterns that lead to this vulnerability include:

• Direct use of $_GET, $_POST, or $_REQUEST parameters in file inclusion statements
• Inadequate path traversal filtering
• Missing whitelist validation for allowed file paths
• Absence of basename extraction before file inclusion

Attack Vector

The attack vector is network-based, meaning attackers can exploit this vulnerability remotely without requiring local access to the target system. The exploitation flow typically involves:

1. Reconnaissance - Attacker identifies WordPress installations running the vulnerable Massive Dynamic theme
2. Payload Crafting - Attacker constructs a malicious request containing path traversal sequences or remote file URLs
3. Exploitation - The malicious request is sent to a vulnerable endpoint that processes file inclusion
4. Code Execution - If successful, the attacker's code executes with the privileges of the web server process

For Local File Inclusion attacks, adversaries may target sensitive files such as /etc/passwd, wp-config.php, or PHP session files. More advanced attacks leverage log poisoning or other techniques to achieve remote code execution through LFI alone.

The vulnerability requires no authentication (unauthenticated access) and no user interaction, making it particularly dangerous for exposed WordPress installations. For detailed technical information, refer to the Patchstack WordPress Vulnerability Advisory.

Detection Methods for CVE-2025-26916

Indicators of Compromise

• Unusual web server access logs showing path traversal patterns (e.g., ../, ..%2f, ....//) in request parameters
• Requests targeting theme files with suspicious query parameters containing file paths
• Web server error logs indicating failed file inclusion attempts or PHP warnings related to include/require functions
• Presence of unexpected PHP files in upload directories or theme folders
• Evidence of accessed sensitive configuration files such as wp-config.php in access logs

Detection Strategies

• Deploy Web Application Firewall (WAF) rules to detect and block path traversal patterns and remote file inclusion attempts
• Implement file integrity monitoring on WordPress installations to detect unauthorized file modifications
• Monitor PHP error logs for include/require-related warnings and errors that may indicate exploitation attempts
• Use intrusion detection systems (IDS) with signatures for common LFI/RFI attack patterns
• Review access logs for requests containing null bytes, URL encoding of path traversal sequences, or references to remote URLs in parameters

Monitoring Recommendations

• Enable comprehensive logging for all WordPress theme-related endpoints
• Configure real-time alerting for detected path traversal or file inclusion attack patterns
• Monitor for unexpected outbound connections from the web server that may indicate successful RFI exploitation
• Track changes to PHP configuration files, particularly modifications to allow_url_include and allow_url_fopen directives

How to Mitigate CVE-2025-26916

Immediate Actions Required

• Identify all WordPress installations using the Massive Dynamic theme and determine the installed version
• Update the Massive Dynamic theme to the latest patched version immediately
• If an update is not available, consider temporarily disabling or replacing the theme until a patch is released
• Review web server logs for signs of exploitation attempts or successful compromise
• Ensure PHP configuration has allow_url_include disabled to prevent remote file inclusion attacks

Patch Information

The vulnerability affects EPC Massive Dynamic theme versions through 8.2. Site administrators should check for available updates through the WordPress theme management interface or contact the theme vendor directly. Review the Patchstack security advisory for the latest patch status and version information.

Workarounds

• Disable remote file inclusion at the PHP level by setting allow_url_include = Off in php.ini
• Implement WAF rules to block requests containing path traversal sequences targeting theme endpoints
• Restrict file system permissions to limit the impact of successful LFI exploitation
• Use a security plugin that provides virtual patching capabilities for known WordPress vulnerabilities
• Consider placing the WordPress installation behind additional network security controls until patching is complete

# PHP configuration hardening - add to php.ini
allow_url_include = Off
allow_url_fopen = Off
open_basedir = /var/www/html:/tmp

# Apache/htaccess rule to block common LFI patterns
# Add to .htaccess in WordPress root
RewriteEngine On
RewriteCond %{QUERY_STRING} (\.\./) [NC,OR]
RewriteCond %{QUERY_STRING} (\.\.%2f) [NC,OR]
RewriteCond %{QUERY_STRING} (etc/passwd) [NC]
RewriteRule .* - [F,L]