MailerLite Signup Forms Plugin for WordPress Stored Cross-Site Scripting Vulnerability

A stored cross-site scripting vulnerability has been identified in the MailerLite Signup Forms (official) plugin for WordPress, affecting versions through 1.7.16. The issue arises from inadequate input sanitization and output escaping, allowing authenticated attackers with administrator privileges to inject arbitrary scripts into pages. These scripts are executed when a user accesses the compromised page.

Impact

Exploitation of this vulnerability allows for stored cross-site scripting, where injected scripts are executed in the context of the user viewing the page.

Reproduction

To reproduce this vulnerability, an authenticated user with administrator access can inject scripts through the 'form_description' and 'success_message' parameters when creating or editing a signup form. The injected scripts will be executed when the form is viewed by users.

Remediation

Users are advised to update the MailerLite Signup Forms plugin to version 1.7.17 or later.