Stored Cross-Site Scripting in Fluent Forms WordPress Plugin

Executive Summary

This is a Stored Cross-Site Scripting (XSS) vulnerability in the Fluent Forms WordPress plugin versions before 6.2.6. It occurs because the plugin fails to sanitize and escape a form field configuration setting before outputting it in an inline script when a form is rendered. This allows users with low privileges, such as Contributors in a multisite setup, to inject malicious scripts that execute in the browsers of visitors viewing the form.

Useful 0 Not Useful 0

Detection Guidance

Check if Fluent Forms plugin version is below 6.2.6 by inspecting the WordPress admin panel under Plugins. Look for forms with Date/Time fields and review the date_config setting for unsanitized input. Use browser developer tools to inspect inline scripts for malicious payloads in rendered forms.

Useful 0 Not Useful 0

Impact Analysis

An attacker with a Contributor role could inject malicious scripts into forms. When administrators or visitors view these forms, the scripts execute, potentially stealing sensitive data, session cookies, or performing actions on their behalf. In some cases, this could escalate to granting the attacker full access to Fluent Forms.

Useful 0 Not Useful 0

Compliance Impact

This vulnerability could lead to unauthorized access to user data, violating GDPR and HIPAA compliance requirements. Stored XSS attacks may expose personal or health information, resulting in legal penalties, reputational damage, and loss of trust.

Useful 0 Not Useful 0

Mitigation Strategies

Update Fluent Forms to version 6.2.6 or later immediately. Remove Contributor access to form management if not required. Disable multisite delegation of form permissions to Contributors. Review all forms for suspicious Date/Time field configurations and remove any untrusted user-created forms.

Useful 0 Not Useful 0