MP Customize Login Page <= 1.0 - Cross-Site Request Forgery to Settings Update

Summary

The MP Customize Login Page plugin for WordPress is vulnerable to Cross-Site Request Forgery (CSRF) in all versions up to and including 1.0. This is due to a completely broken nonce validation in the enter_mpclp_login_options() function, which contains an inverted check (if wp_verify_nonce(...) { return false; }) and is missing the required action parameter for wp_verify_nonce(). As a result, the nonce check is effectively dead code: it never blocks malicious requests because a CSRF-supplied empty/invalid nonce always returns false, satisfying the inverted condition to continue execution. Furthermore, the settings-update handler is hooked on init without any capability check. This makes it possible for unauthenticated attackers to modify all plugin setting, including login page background, logo URL, image dimensions, button colors, and login message, by tricking a logged-in administrator into submitting a crafted request.