Kali Forms < 2.4.21 - Unauthenticated Remote Code Execution via 'thisPermalink' Field Parameter

Description

The Kali Forms — Contact Form & Drag-and-Drop Builder plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 2.4.20 via the _save_data function. This is due to insufficient validation of the 'thisPermalink' field value before it overwrites a trusted callable placeholder, allowing attacker-controlled strings to reach call_user_func() in _save_data(). This makes it possible for unauthenticated attackers to execute code on the server. Exploitation requires the target form to define a field with a name matching one of the reserved placeholder keys ('thisPermalink', 'entryCounter', or 'submission_link'), as check_if_placeholders_changed() only processes POST keys present in the form's field_type_map.