Deserialization of Untrusted Data in Themify Popup

Executive Summary

CVE-2026-56037 is a PHP Object Injection vulnerability found in the WordPress Themify Popup Plugin versions 1.4.3 and below. It arises from the deserialization of untrusted data, which allows attackers to inject malicious objects into the application.

This vulnerability can be exploited if a suitable POP (Property Oriented Programming) chain exists, enabling attackers to perform various malicious actions such as code injection, SQL injection, path traversal, and denial of service.

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Impact Analysis

If exploited, this vulnerability can have severe impacts including unauthorized code execution, data breaches through SQL injection, unauthorized file access via path traversal, and service disruption through denial of service attacks.

All websites using the vulnerable plugin, regardless of their size or popularity, are at risk and could be targeted in mass-exploit campaigns.

Users are strongly advised to update to version 1.4.4 immediately or apply mitigation rules provided by Patchstack to block attacks until the update is applied.

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Detection Guidance

Detection of this vulnerability involves identifying if the Themify Popup Plugin version 1.4.3 or below is in use on your WordPress site.

You can check the plugin version by running commands on your server to list the installed WordPress plugins and their versions.

• Use WP-CLI command: wp plugin list | grep themify-popup
• Check the plugin version in the WordPress admin dashboard under Plugins.

Additionally, monitoring network traffic for suspicious payloads that attempt PHP object injection could help detect exploitation attempts, but no specific detection commands are provided.

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Mitigation Strategies

The immediate mitigation step is to update the Themify Popup Plugin to version 1.4.4 or later, which contains the patch for this vulnerability.

Until the update can be applied, it is advised to implement the mitigation rule provided by Patchstack to block attacks targeting this vulnerability.

Regularly monitor your site for suspicious activity and consider restricting access or disabling the plugin if an update is not immediately possible.

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