Weakness
The WowOptin: Next-Gen Popup Maker WordPress plugin before 1.4.38 does not have proper authorization on a REST endpoint, allowing unauthenticated users to disable all of the site's opt-in forms and insert new template-based opt-in rows into the database.
References
Find the bug before an attacker does.
Sign in with GitHub and run your first audit in under a minute. The free plan needs no credit card.