Forminator Forms <= 1.57.3.1 - Insecure Direct Object Reference to Unauthenticated Arbitrary Draft Deletion and Takeover via 'previous_draft_id' Parameter

The Forminator Forms – Contact Form, Payment Form & Custom Form Builder plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 1.57.3.1 via the 'previous_draft_id' parameter due to missing validation on a user controlled key. This makes it possible for unauthenticated attackers to delete arbitrary saved drafts belonging to other users and take over those draft identifiers by overwriting them with attacker-controlled form submissions. This requires the attacker to have obtained a victim's draft_id, which may be harvested from a shared "continue later" link; the nominally present nonce check is effectively bypassed because the nonce is publicly obtainable by any unauthenticated visitor loading a form page.