Broken Access Control means users can access data or actions they shouldn’t be allowed to. It’s the top risk in the OWASP Top 10 because it’s common and dangerous. Examples include viewing other users’ profiles, accessing admin pages, or changing roles without permission. This usually happens when permission checks are missing or done only on the front end. The fix is simple: always check permissions on the server, deny access by default, and test regularly to make sure the rules work.
OWASP A01:2021 Broken Access Control Visual Explainer
OWASP A01:2021 Broken Access Control - The attacker can use valid credentails to access resources beyond the granted permissions. Including if permissions are ReadOnly or no access
Introduction to A01: Broken Access Control
This issue often flies under the radar because users aren’t supposed to try things outside their role, but attackers will. They’ll guess URLs, tamper with parameters, or directly call APIs to find weaknesses. That’s why it's critical to build access rules into every part of the system, not just rely on hiding buttons or trusting the front end. Logging and monitoring can help spot suspicious activity, but prevention is key. Proper access control should be consistent, tested often, and treated as a core security requirement, not an afterthought.
