In lunary-ai/lunary version 1.4.28, the /checklists/:id route allows low-privilege users to modify checklists by sending a PATCH request. The route lacks proper access control, such as middleware to ensure that only authorized users (e.g., project owners or admins) can modify checklist data. This vulnerability allows any user associated with the project, regardless of their role, to modify checklists, including changing the slug or data fields, which can lead to tampering with essential project workflows, altering business logic, and introducing errors that undermine integrity.