You log in as user #1001. You change the URL to user #1000. Suddenly, you’re looking at someone else’s invoices, emails, and phone numbers. No hack, no injection — just a missing access control. Welcome to the world of IDOR, one of the most rewarding bug bounty findings.
Press enter or click to view image in full size
Welcome back to the Bug Bounty Bootcamp. You’ve exploited complex vulnerabilities like SQL injection, XSS, and file upload RCE. Now, we tackle something deceptively simple yet incredibly common: Insecure Direct Object Reference (IDOR) . This isn’t about breaking syntax or bypassing filters. It’s about asking the server for something you shouldn’t have — and the server just handing it over. IDOR vulnerabilities arise when an application uses user-supplied input (like an ID in a URL or API request) to directly access an object (a profile, an order, a document) without verifying that the requesting user actually owns or has permission to access that object. The fix is often a single line of authorization logic. But when that line is missing, the results can be catastrophic.