NL Portal Backend Libraries provide backend components for Dutch government portals that interact with residents, customers, suppliers, and partner organizations. The "nl.nl-portal:taak" package from version 1.5.0 through 3.0.0 fails to verify ownership when processing the "submitTaakV2" GraphQL mutation, allowing an authenticated user who knows or guesses another user’s task ID to read its form data, overwrite its submitted data, and mark the task as completed. Version 3.0.1 contains a patch. As a workaround, block the "submitTaakV2" mutation at the API gateway or restrict the "/graphql" endpoint to trusted networks