What is authentication bypass in a web application?¶

Authentication bypass avoids or defeats the control meant to restrict a web function to authenticated users. Access to a protected-looking page does not prove bypass if a valid session existed or the sensitive action remained separately protected.

Identify the expected control¶

Establish the function, required authentication and role, request or token presented, gateway processing, application response and associated session. Possible mechanisms include a flaw, access-control misconfiguration, session manipulation, token misuse or an unprotected endpoint.

Preserve failed attempts and changes in parameters or sequence. They may show how the actor learned the control before reaching a protected function.

Define the exact result¶

A bypass may expose one object, impersonate a user or permit an administrative action while other controls still work. Prove the data or action available and any repeated use rather than describing the whole application as unauthenticated.

Current product behaviour may need vendor or specialist verification. Keep valid-session use, default credentials, misconfiguration and exploitable bypass as distinct explanations.