CVE-2025-39588: Ultimate Store Kit Object Injection Flaw

CVE-2025-39588 Overview

CVE-2025-39588 is a critical Deserialization of Untrusted Data vulnerability affecting the Ultimate Store Kit Elementor Addons WordPress plugin developed by bdthemes. This vulnerability allows attackers to perform Object Injection attacks by exploiting insecure deserialization of user-supplied data. The flaw impacts all versions of the plugin through 2.4.0.

Object Injection vulnerabilities in WordPress plugins are particularly dangerous as they can lead to remote code execution, authentication bypass, or complete site compromise when a suitable gadget chain exists within the application's codebase or loaded libraries.

Critical Impact

Unauthenticated attackers can exploit this vulnerability remotely without user interaction to potentially achieve full system compromise, including arbitrary code execution, data theft, and complete control over affected WordPress installations.

Affected Products

• Ultimate Store Kit Elementor Addons versions up to and including 2.4.0
• WordPress installations using vulnerable versions of the plugin
• WooCommerce-integrated sites leveraging Ultimate Store Kit functionality

Discovery Timeline

• April 17, 2025 - CVE-2025-39588 published to NVD
• April 17, 2025 - Last updated in NVD database

Technical Details for CVE-2025-39588

Vulnerability Analysis

This vulnerability stems from improper handling of serialized data within the Ultimate Store Kit Elementor Addons plugin. The plugin fails to properly validate or sanitize serialized input before passing it to PHP's unserialize() function, creating a classic CWE-502 (Deserialization of Untrusted Data) condition.

When an attacker supplies a maliciously crafted serialized object, the PHP interpreter will instantiate the object and execute any magic methods such as __wakeup(), __destruct(), or __toString(). If suitable "gadget" classes exist within WordPress core, installed plugins, or the PHP environment, attackers can chain these methods to achieve arbitrary code execution or other malicious outcomes.

The network-accessible nature of this vulnerability means attackers can exploit it remotely without any authentication or user interaction, significantly increasing the risk and potential attack surface.

Root Cause

The root cause is the use of PHP's unserialize() function on untrusted user input without proper validation. The plugin accepts serialized data through network requests and deserializes it directly, trusting that the data structure and object types are safe. This trust assumption is fundamentally flawed since attackers can craft serialized strings representing arbitrary object types with attacker-controlled property values.

PHP Object Injection occurs because serialized data contains class names and property values that PHP blindly reconstructs into live objects. When combined with existing class definitions that have exploitable magic methods, this creates a powerful attack primitive.

Attack Vector

The attack is executed over the network against WordPress installations running vulnerable versions of the Ultimate Store Kit Elementor Addons plugin. An attacker would:

1. Identify a WordPress site using Ultimate Store Kit Elementor Addons version 2.4.0 or earlier
2. Craft a malicious serialized PHP object containing an exploit payload
3. Submit the serialized payload through the vulnerable input vector
4. The plugin deserializes the object, triggering magic method execution
5. If a suitable gadget chain exists, arbitrary code execution or other impacts occur

The vulnerability requires no privileges and no user interaction, making it highly exploitable in automated attack scenarios.

For detailed technical information about this vulnerability, refer to the Patchstack Security Advisory.

Detection Methods for CVE-2025-39588

Indicators of Compromise

• Unusual serialized data strings containing class names in web server access logs
• Presence of PHP serialized strings with O: prefix in POST data or request parameters
• Unexpected file creation or modification in the WordPress installation
• Anomalous PHP process execution or outbound network connections
• Web application firewall alerts for serialization-related attack patterns

Detection Strategies

• Monitor web server logs for requests containing serialized PHP objects (patterns like O:[0-9]+: or a:[0-9]+:)
• Deploy web application firewall rules to detect and block serialized object injection attempts
• Implement file integrity monitoring on WordPress core files and plugin directories
• Enable PHP error logging and monitor for deserialization-related errors
• Use endpoint detection solutions to identify post-exploitation activities

Monitoring Recommendations

• Configure centralized logging for all WordPress access and error logs
• Set up alerts for unusual patterns in request bodies targeting Elementor-related endpoints
• Monitor for new or modified PHP files in the wp-content/plugins/ directory
• Track outbound network connections from the web server process
• Review WordPress admin activity logs for unauthorized changes

How to Mitigate CVE-2025-39588

Immediate Actions Required

• Update Ultimate Store Kit Elementor Addons to a patched version immediately
• If an update is not available, deactivate and remove the vulnerable plugin
• Review WordPress access logs for potential exploitation attempts
• Perform a security audit of the WordPress installation for signs of compromise
• Consider implementing a web application firewall with serialization attack detection

Patch Information

A patched version addressing this vulnerability should be obtained from the official WordPress plugin repository or directly from bdthemes. Site administrators should update to a version higher than 2.4.0 as soon as a security update becomes available. Monitor the Patchstack Advisory for update information.

Workarounds

• Deactivate the Ultimate Store Kit Elementor Addons plugin until a patch is available
• Implement web application firewall rules to block serialized PHP object patterns in requests
• Restrict access to WordPress admin and plugin functionality to trusted IP addresses
• Enable WordPress security hardening measures and limit plugin permissions
• Consider using alternative WooCommerce/Elementor integration plugins that are not affected

# WordPress CLI commands to check and deactivate vulnerable plugin
# Check if the vulnerable plugin is installed
wp plugin list --fields=name,version | grep ultimate-store-kit

# Deactivate the plugin if vulnerable version is found
wp plugin deactivate ultimate-store-kit

# Alternatively, completely remove the plugin
wp plugin delete ultimate-store-kit