An Insecure Direct Object Reference (IDOR) vulnerability exists in the lunary-ai/lunary repository, version 0.3.0, within the project update endpoint. The vulnerability allows authenticated users to modify the name of any project within the system without proper authorization checks, by directly referencing the project's ID in the PATCH request to the '/v1/projects/:projectId' endpoint. This issue arises because the endpoint does not verify if the provided project ID belongs to the currently authenticated user, enabling unauthorized modifications across different organizational projects.