In lunary-ai/lunary before version 1.6.3, the application allows the creation of evaluators without enforcing a unique constraint on the combination of projectId and slug. This allows an attacker to overwrite existing data by submitting a POST request with the same slug as an existing evaluator. The lack of database constraints or application-layer validation to prevent duplicates exposes the application to data integrity issues. This vulnerability can result in corrupted data and potentially malicious actions, impairing the system's functionality.