MailerPress <= 2.0.4 - Authenticated (Author+) Stored Cross-Site Scripting via Campaign HTML Content Field

The MailerPress – Email Marketing, Newsletter, Email Automation & WooCommerce Emails plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Campaign HTML Content Field in all versions up to, and including, 2.0.4 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with author-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The public-facing campaign preview endpoint (/mp-email/{id}-slug/) is not affected by this vulnerability, as it applies a Content-Security-Policy header blocking all inline scripts; exploitation is limited to the admin dashboard preview.