CVE-2026-81534 in Email Customizer for WooCommerce Plugin
Summary
by MITRE • 10/15/2026
The Email Customizer for WooCommerce (Pro) plugin for WordPress is vulnerable to Remote Code Execution in versions up to, and including, 3.9.5. This is due to insufficient authorization and input sanitization in the send_test_mail() function, which allows user-controlled PHP code to be written to executable files in the uploads directory. This makes it possible for authenticated attackers, with subscriber-level access and above, to execute arbitrary PHP code on the server, leading to full site compromise.
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Analysis
by VulDB Data Team • 10/15/2026
The Email Customizer for WooCommerce (Pro) plugin represents a significant security risk when deployed in versions up to 3.9.5 due to critical flaws that facilitate Remote Code Execution. This vulnerability stems from insufficient authorization checks and inadequate input sanitization within the send_test_mail() function of the plugin's codebase. The core technical flaw lies in the application's failure to properly validate or sanitize user-supplied data before processing it for email template generation. Specifically, the function accepts parameters that are directly written into PHP files located within the WordPress uploads directory without enforcing strict type checking or escaping mechanisms. This architectural oversight allows an attacker to inject arbitrary PHP code as part of the input payload, which is then saved and subsequently executed by the web server when the compromised file is accessed.
From a technical perspective, this vulnerability aligns with CWE-94 Improper Control of Generation of Code (Code Injection) and CWE-269 Improvement of Access Control due to insufficient authorization checks. The lack of proper sanitization permits the injection of executable code into files that are typically intended for static content or configuration data rather than active scripts. Because the uploads directory is often configured with execute permissions in many WordPress hosting environments, particularly those using Apache or Nginx with specific rewrite rules, the injected PHP code becomes immediately actionable. This transforms a simple input validation failure into a severe server-side compromise vector where user-controlled strings are converted directly into executable instructions on the backend infrastructure.
The operational impact of this vulnerability is profound and extends beyond mere data exposure to complete system takeover. An authenticated attacker with subscriber-level access or higher can exploit this flaw to achieve Remote Code Execution without requiring administrative privileges, thereby lowering the barrier for entry significantly. Once arbitrary PHP code is executed, the attacker gains the ability to read sensitive database credentials, exfiltrate customer payment information stored in WooCommerce, modify site content, install persistent backdoors such as web shells, and pivot further into the internal network if server-side vulnerabilities exist. This level of access effectively results in a full compromise of the WordPress installation and potentially the underlying hosting environment, leading to severe reputational damage, regulatory non-compliance under standards like PCI DSS or GDPR, and substantial financial losses for affected businesses.
To mitigate this risk, immediate action is required by upgrading the Email Customizer for WooCommerce (Pro) plugin to version 3.9.6 or later, where these authorization and sanitization issues have been addressed. In addition to updating the software, administrators should implement strict input validation practices across all user-facing endpoints, ensuring that only expected data types are processed and that special characters are properly escaped before any file operations occur. It is also advisable to review server configurations to restrict execute permissions on directories containing uploaded files unless absolutely necessary for application functionality. Furthermore, deploying a Web Application Firewall can provide an additional layer of defense by detecting and blocking common code injection patterns in HTTP requests. Regular security audits and the principle of least privilege should be enforced to ensure that user roles have only the minimum access required for their specific tasks, thereby limiting the potential impact if such vulnerabilities are discovered in future updates.