OWASP Top 10 #1: Understanding Broken Access Control (Beginner's Guide)

Short summary

Broken Access Control, OWASP's #1 vulnerability, occurs when users access resources beyond their intended permissions—often via unprotected URLs, client-side role elevation, or platform misconfiguration. Always validate authorization server-side and never trust client-controlled data like cookies, hidden fields, parameters, or JSON values. The fundamental principle: authorization decisions belong entirely to the server, not the client interface.

• •Never trust client-side authorization data (cookies, hidden fields, parameters, JSON)
• •Always validate user permissions server-side before granting access
• •Hidden or obscured URLs provide no security without proper server-side authorization checks

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