CVE-2025-52761: WP Funnel Manager Object Injection Flaw

CVE-2025-52761 Overview

CVE-2025-52761 is a critical Insecure Deserialization vulnerability affecting the WP Funnel Manager WordPress plugin developed by manfcarlo. The vulnerability allows attackers to exploit PHP Object Injection through deserialization of untrusted data, potentially enabling remote code execution, unauthorized data access, or complete site compromise. This issue affects WP Funnel Manager versions through 1.4.0.

Critical Impact

This PHP Object Injection vulnerability can be exploited remotely without authentication, potentially allowing attackers to execute arbitrary code, manipulate application data, or gain complete control over affected WordPress installations.

Affected Products

• WP Funnel Manager plugin versions from n/a through 1.4.0
• WordPress installations running vulnerable WP Funnel Manager versions
• Sites with the wp-funnel-manager plugin active

Discovery Timeline

• 2025-08-28 - CVE-2025-52761 published to NVD
• 2025-08-29 - Last updated in NVD database

Technical Details for CVE-2025-52761

Vulnerability Analysis

This vulnerability falls under CWE-502 (Deserialization of Untrusted Data), a category of flaws where applications deserialize data from untrusted sources without proper validation. In PHP applications like WordPress plugins, this typically occurs when user-controlled input is passed to the unserialize() function without adequate sanitization.

PHP Object Injection vulnerabilities are particularly dangerous because they can lead to a variety of attack outcomes depending on the classes available in the application's autoloader. When an attacker can control the serialized data being deserialized, they can instantiate arbitrary objects and potentially trigger magic methods like __wakeup(), __destruct(), or __toString() to execute malicious code.

The attack can be conducted remotely over the network and requires no authentication or user interaction, making it highly accessible to potential attackers. Successful exploitation could result in complete compromise of confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause of CVE-2025-52761 is the improper handling of serialized data within the WP Funnel Manager plugin. The plugin fails to adequately validate or sanitize serialized input before passing it to PHP's unserialize() function. This allows an attacker to craft malicious serialized payloads that, when deserialized, instantiate dangerous objects with attacker-controlled properties.

WordPress plugins that handle serialized data for storing complex data structures, session management, or configuration settings are particularly susceptible to this type of vulnerability if proper input validation is not implemented.

Attack Vector

The attack vector for this vulnerability is network-based, meaning it can be exploited remotely. An attacker would craft a malicious serialized PHP object and submit it to an endpoint in the WP Funnel Manager plugin that processes serialized data. The malicious payload would typically exploit existing "gadget chains" — sequences of classes and method calls that can be chained together during deserialization to achieve code execution or other malicious outcomes.

Common attack scenarios include:

• Injecting serialized objects through POST/GET parameters
• Manipulating cookie values containing serialized data
• Exploiting AJAX endpoints that process serialized input

The vulnerability does not require any privileges or user interaction, allowing unauthenticated attackers to potentially exploit the flaw directly. For technical details on the specific exploitation vectors, refer to the Patchstack WP Funnel Manager Vulnerability advisory.

Detection Methods for CVE-2025-52761

Indicators of Compromise

• Unusual serialized data patterns in HTTP request logs containing unexpected object references
• Unexpected file modifications in WordPress installation directories
• New administrator accounts or privilege changes without authorized actions
• PHP error logs showing serialization-related warnings or class instantiation errors
• Suspicious outbound network connections from the web server

Detection Strategies

• Monitor web application logs for requests containing serialized PHP objects (patterns like O: followed by class names and properties)
• Implement Web Application Firewall (WAF) rules to detect and block serialized PHP object patterns in user input
• Deploy file integrity monitoring to detect unauthorized changes to WordPress core, plugin, or theme files
• Review access logs for unusual POST requests to WP Funnel Manager endpoints

Monitoring Recommendations

• Enable verbose logging for the WP Funnel Manager plugin and related WordPress activity
• Configure SIEM alerts for patterns matching PHP object injection attempts
• Monitor for new user account creation or privilege escalation events in WordPress
• Track changes to wp-config.php and other critical configuration files

How to Mitigate CVE-2025-52761

Immediate Actions Required

• Update WP Funnel Manager to a patched version if available from the plugin developer
• If no patch is available, consider deactivating and removing the WP Funnel Manager plugin until a fix is released
• Implement WAF rules to block requests containing serialized PHP objects
• Review WordPress user accounts for any unauthorized additions or privilege changes
• Audit server logs for signs of exploitation attempts

Patch Information

A patch for this vulnerability should be obtained from the plugin developer. Organizations should monitor the Patchstack WP Funnel Manager Vulnerability advisory for updates on remediation. Until an official patch is available, the recommended mitigation is to disable the affected plugin.

Workarounds

• Disable the WP Funnel Manager plugin entirely until an official patch is released
• Implement strict input validation at the web server or WAF level to reject serialized PHP data
• Restrict access to WordPress admin and plugin functionality using IP whitelisting or VPN requirements
• Consider using WordPress security plugins that provide virtual patching capabilities

# Disable WP Funnel Manager plugin via WP-CLI
wp plugin deactivate wp-funnel-manager

# Verify the plugin is deactivated
wp plugin list --status=inactive | grep wp-funnel-manager