🔓 IDOR / BOLA: How to Find the #1 API Vulnerability — and Actually Prove It

Broken Object Level Authorization, commonly known as IDOR, is the most frequent serious vulnerability in modern APIs, ranking first on the OWASP API Security Top 10 (2023). These bugs often bypass scanners and code reviews because applications verify user identity but fail to check object ownership. This guide explains what IDOR/BOLA is, how it functions, and how to identify it. Crucially, it demonstrates how to prove the vulnerability exists without accessing real user data.