Open Forms allows users create and publish smart forms. Prior to 3.3.13 and 3.4.5, to be able to cosign, the cosigner receives an e-mail with instructions or a deep-link to start the cosign flow. The submission reference is communicated so that the user can retrieve the submission to be cosigned. Attackers can guess a code or modify the received code to look up arbitrary submissions, after logging in (with DigiD/eHerkenning/... depending on form configuration). This vulnerability is fixed in 3.3.13 and 3.4.5.
Open Forms allows users create and publish smart forms. Prior to versions 3.2.7 and 3.3.3, forms where the prefill data fields are dynamically set to readonly/disabled can be modified by malicious users deliberately trying to modify data they're not supposed to. For regular users, the form fields are marked as readonly and cannot be modified through the user interface. This issue has been patched in versions 3.2.7 and 3.3.3.