Executive Summary

The vulnerability in the Form Maker plugin for WordPress (up to version 1.15.35) is a Stored Cross-Site Scripting (XSS) issue. It occurs because the plugin uses html_entity_decode() on user-supplied hidden field values without properly escaping the output before displaying it in the admin submissions list. This allows an unauthenticated attacker to inject malicious JavaScript code into hidden fields, which then executes in the administrator's browser when they view the submissions list. The root cause is insufficient output sanitization, enabling arbitrary script injection in the admin interface. [1]

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Impact Analysis

This vulnerability can allow unauthenticated attackers to execute arbitrary JavaScript in the context of the WordPress admin interface when an administrator views the form submissions. This can lead to several impacts including theft of administrator credentials or session tokens, unauthorized actions performed with admin privileges, defacement or manipulation of the admin interface, and potentially further compromise of the WordPress site. Because the attack executes in the admin's browser, it can bypass many client-side protections and lead to significant security breaches. [1]

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Detection Guidance

This vulnerability can be detected by checking if your WordPress installation is running the Form Maker plugin version 1.15.35 or earlier, as these versions are vulnerable. Specifically, you can inspect the admin submissions list for any suspicious or unexpected JavaScript code in hidden field values. Since the vulnerability involves stored cross-site scripting via hidden fields, reviewing the plugin's 'Submissions_fm.php' file for the absence of proper escaping (lack of esc_html usage) can also indicate vulnerability. There are no specific network commands provided, but you can use WordPress CLI commands to check the plugin version, for example: `wp plugin get form-maker --field=version`. Additionally, monitoring admin submissions for unusual scripts or payloads in hidden fields can help detect exploitation attempts. [1, 2]

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Mitigation Strategies

The immediate mitigation step is to update the Form Maker plugin to version 1.15.36 or later, where the vulnerability has been fixed by enforcing proper output escaping (using esc_html) on hidden field values and adding MIME type validation to prevent unsafe file uploads such as SVG files. If updating is not immediately possible, restrict access to the WordPress admin submissions list to trusted administrators only, and consider applying manual code patches to escape output properly in 'admin/views/Submissions_fm.php'. Also, monitor and block any suspicious file uploads, especially SVG files, to reduce risk. [1]

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Compliance Impact

The vulnerability in the Form Maker plugin allows unauthenticated attackers to inject arbitrary scripts in the admin submissions view, which could lead to unauthorized access or manipulation of sensitive data handled by the plugin.

Such a security flaw can impact compliance with standards like GDPR and HIPAA because it increases the risk of data breaches or unauthorized data exposure through cross-site scripting attacks.

By enabling script execution in the admin interface, attackers might compromise the confidentiality and integrity of personal or protected health information managed via the plugin, potentially violating regulatory requirements for data protection and security.

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