How to Secure Fintech REST APIs Against BOLA Vulnerabilities

Broken Object Level Authorization (BOLA) occurs when a REST API exposes an object identifier—such as an account, transaction, or loan ID — without verifying whether the authenticated user is authorized to access that specific resource. To protect fintech REST APIs , implement server-side authorization checks for every object request , validate permissions using the user’s authenticated context and resource ownership, and avoid relying on client-supplied IDs alone. Using unpredictable identifiers such as UUID v4 or ULIDs can reduce object enumeration, but they should be treated as an additional