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JWT (JSON Web Token) Security Risks: Common Vulnerabilities and Exploits Every Bug Hunter Should Know
Ever wondered how web apps authenticate users without storing sessions?
Welcome to the realm of JSON Web Tokens (JWTs), a crucial component of secure authentication, API interactions, and modern web security. Whether you’re a developer, a penetration tester, or simply eager to understand token-based authentication, this guide will provide a clear and comprehensive breakdown.
What is a JWT?
A JSON Web Token (JWT) is a lightweight, self-contained token designed for securely exchanging information between parties in JSON format. Unlike traditional session-based authentication, JWTs enable stateless authentication, offering scalability, efficiency, and broad adoption in modern applications.
Structure of a JWT
A JWT is composed of three components, all Base64-encoded and separated by dots (.):
Header: Specifies the signing algorithm and token type.
Payload: Contains claims (user information, expiration, etc.).
Signature: Ensures the token’s integrity, stopping tampering.
Example of a JWT:
A real JWT looks like this:
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.
eyJ1c2VySWQiOiIxMjM0NTY3ODkwIiwidXNlcm5hbWUiOiJqb2huZG9lIn0.
SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c
Why is JWT So Famous?
✅ Stateless Authentication — No need for server-side sessions.
✅ Compact & Fast — Ideal for mobile & web apps.
✅ Secure Data Transmission — Encrypted & tamper-proof with signatures.
✅ Cross-Domain Authentication — Perfect for APIs & Single Sign-On (SSO).
