What are the biggest API security mistakes developers make?

All answers to this question.

The absolute most widespread mistake is Broken Object Level Authorization, commonly known as BOLA. Developers often assume that if a user has successfully authenticated with a valid token, they are automatically allowed to access any record in the entire database. They create endpoints that fetch records based purely on user-supplied parameters like a sequential ID in the URL. Attackers can easily manipulate these ID sequences to scrape massive amounts of sensitive data. You must implement strict, fine-grained ownership checks on every single database query to ensure the requesting entity owns that object.

   Answered 2025-06-18 by Victoria Simmons

Why do backend teams consistently fail to implement basic rate limiting and request throttling on public-facing authentication and payload endpoints before moving code to production environments?

   Answered 2025-07-02 by Lawrence Fish

• Lawrence, it usually comes down to rushing delivery milestones. Teams often treat rate limiting as an infrastructure problem to be handled later by DevOps or a web application firewall rather than building it into the application layer logic. This oversight leaves the backend completely exposed to credential stuffing attacks and resource exhaustion.

     Commented 2025-07-08 by Gregory Peck

Another major mistake is excessive data exposure. Developers frequently serialize entire database objects and return them to the client-side UI, expecting the frontend browser code to filter out sensitive properties.

   Answered 2025-07-20 by Diana Ross

• I completely agree with you, Diana. Attackers can easily open the network tab in their browser tools and view the raw JSON payload, which often exposes hidden properties like internal user IDs, roles, or personal data.

     Commented 2025-07-26 by Arthur Pendelton