An Insecure Direct Object Reference (IDOR) vulnerability was identified in the "POST /v1/templates" endpoint of the Lunary API, affecting versions up to 0.8.8. This vulnerability allows authenticated users to create templates in another user's project by altering the "projectId" query parameter. The root cause of this issue is the absence of server-side validation to ensure that the authenticated user owns the specified "projectId". The vulnerability has been addressed in version 1.9.23.