CVE-2025-67944: Nelio AB Testing Code Injection RCE Flaw

CVE-2025-67944 Overview

CVE-2025-67944 is a Code Injection vulnerability affecting the Nelio AB Testing WordPress plugin developed by Nelio Software. This vulnerability allows attackers to inject and execute arbitrary code within affected WordPress installations, potentially leading to complete site compromise.

Critical Impact

Successful exploitation of this code injection vulnerability could allow attackers to execute arbitrary code on the server, potentially leading to full WordPress site takeover, data exfiltration, or malware deployment.

Affected Products

• Nelio AB Testing WordPress Plugin versions through 8.1.8
• WordPress installations running vulnerable versions of nelio-ab-testing

Discovery Timeline

• 2026-01-22 - CVE CVE-2025-67944 published to NVD
• 2026-01-22 - Last updated in NVD database

Technical Details for CVE-2025-67944

Vulnerability Analysis

This vulnerability is classified as CWE-94: Improper Control of Generation of Code ('Code Injection'). The Nelio AB Testing plugin fails to properly sanitize or validate user-supplied input before incorporating it into dynamically generated code. This fundamental flaw allows malicious actors to craft specially formed input that gets interpreted and executed as code rather than data.

Code injection vulnerabilities in WordPress plugins are particularly dangerous because they can provide attackers with the same privileges as the web server process. In the context of a WordPress environment, this often means the ability to read and modify database contents, access sensitive configuration files including database credentials, install backdoors, or pivot to attack other sites on shared hosting environments.

Root Cause

The root cause of CVE-2025-67944 lies in the improper control of code generation within the Nelio AB Testing plugin. The plugin fails to implement adequate input validation and sanitization mechanisms before processing user-controlled data in a code execution context. This allows untrusted input to be interpreted as executable code rather than being treated as inert data.

Attack Vector

The attack vector for this vulnerability involves supplying malicious input to the Nelio AB Testing plugin that gets processed without proper sanitization. An attacker could exploit this vulnerability by:

1. Identifying input fields or parameters processed by the vulnerable plugin
2. Crafting a malicious payload containing executable code
3. Submitting the payload through the vulnerable input vector
4. The plugin processes the input and executes the injected code

The vulnerability allows for arbitrary code execution, meaning attackers can execute commands with the privileges of the web server, potentially leading to complete WordPress installation compromise.

Detection Methods for CVE-2025-67944

Indicators of Compromise

• Unexpected PHP files or scripts appearing in plugin directories
• Unusual outbound network connections from the WordPress server
• Modified plugin files with injected code snippets
• Suspicious entries in WordPress or web server access logs involving the nelio-ab-testing plugin
• Unauthorized administrative accounts or privilege changes

Detection Strategies

• Monitor web server logs for suspicious requests targeting /wp-content/plugins/nelio-ab-testing/ paths
• Implement file integrity monitoring on WordPress plugin directories to detect unauthorized modifications
• Deploy Web Application Firewall (WAF) rules to detect code injection patterns in requests
• Review plugin activity logs for unusual behavior or unexpected code execution

Monitoring Recommendations

• Enable verbose logging for the WordPress installation and associated plugins
• Configure alerting for any file changes within the nelio-ab-testing plugin directory
• Monitor server resource usage for anomalies that could indicate malicious code execution
• Implement regular security scanning of WordPress installations using tools like WPScan

How to Mitigate CVE-2025-67944

Immediate Actions Required

• Check if Nelio AB Testing plugin is installed and verify the installed version
• If running version 8.1.8 or earlier, immediately update to the latest patched version
• Temporarily deactivate the Nelio AB Testing plugin until a patch is applied
• Review server logs for any indicators of exploitation
• Consider implementing additional WAF rules to block code injection attempts

Patch Information

Site administrators should update the Nelio AB Testing plugin to the latest available version that addresses this vulnerability. Check the Patchstack Vulnerability Report for updated patch information and remediation guidance from the vendor.

Workarounds

• Deactivate the Nelio AB Testing plugin until an official patch is available
• Implement Web Application Firewall rules to filter malicious input targeting the plugin
• Restrict access to WordPress admin areas using IP allowlisting
• Enable WordPress security plugins that provide additional input validation layers
• Consider temporary removal of the plugin if A/B testing functionality is not critical

If a patched version is not yet available, administrators should consider these temporary mitigation steps:

# Deactivate the vulnerable plugin via WP-CLI
wp plugin deactivate nelio-ab-testing

# Verify plugin is deactivated
wp plugin list --status=inactive | grep nelio-ab-testing

# Set restrictive permissions on plugin directory as additional precaution
chmod -R 444 /var/www/html/wp-content/plugins/nelio-ab-testing/