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.
When the product encounters an error condition or failure, its design requires it to fall back to a state that is less secure than other options that are available, such as selecting the weakest encryption algorithm or using the most permissive access control restrictions.