TDuck survey form through 6.0 fails to validate write passwords on submission endpoints, enforcing the check only on the front end. Remote unauthenticated attackers can submit form entries directly to public submission APIs without providing the password by using the form key from share links.

TDuck survey form through 6.0 fails to enforce form fill-in restrictions on the authenticated submission endpoint POST /user/form/data/create. Authenticated attackers who know a form's key can submit unlimited entries to any form, bypassing publish status, time window, quota, and per-IP restrictions to falsify collected results.

TDuck survey form 6.0 contains an information disclosure vulnerability in FormAuthUtils.hasPermission that fails open when a form does not exist, allowing authenticated users to access deleted form submissions. Attackers can read orphaned submission data including personal information by providing a known dataId to the GET /user/form/data/details endpoint after the form has been permanently deleted.

TDuck survey form through version 5.0 contains an authorization bypass vulnerability in the POST /user/form/data/update endpoint that allows authenticated users to overwrite other users' form submission data. Attackers can discover submission identifiers allocated in narrow ranges and modify arbitrary form responses containing personal data by sending update requests without ownership validation.