jwt▌

You are an expert in JSON Web Token (JWT) security implementation. Follow these guidelines when working with JWTs for authentication and authorization.

Tests API authentication mechanisms for weaknesses including broken token validation, missing authentication on endpoints, weak password policies, credential stuffing susceptibility, token leakage in URLs or logs, and session management flaws. The tester evaluates JWT implementation, API key handling, OAuth flows, and session token entropy to identify authentication bypasses. Maps to OWASP API2:2023 Broken Authentication. Activates for requests involving API authentication testing, token validation assessment, credential security testing, or API auth bypass.

Execute and test the JWT none algorithm attack to bypass signature verification by manipulating the alg header field in JSON Web Tokens.

Assessing JSON Web Token implementations for cryptographic weaknesses, algorithm confusion attacks, and authorization bypass vulnerabilities during security engagements.

Exploits JWT algorithm confusion vulnerabilities where the server's token verification library accepts the algorithm specified in the JWT header rather than enforcing a fixed algorithm. The tester manipulates the alg header to switch from RS256 to HS256 (using the RSA public key as the HMAC secret), sets alg to none to bypass signature verification, or exploits kid/jku/x5u header injection to supply attacker-controlled keys. Activates for requests involving JWT algorithm confusion, alg none attack, key confusion attack, or JWT signature bypass.

JSON Web Tokens (JWT) defined in RFC 7519 are compact, URL-safe tokens used for authentication and authorization in web applications. This skill covers implementing secure JWT signing with HMAC-SHA256

Test JWT implementations for critical vulnerabilities including algorithm confusion, none algorithm bypass, kid parameter injection, and weak secret exploitation to achieve authentication bypass and privilege escalation.

JWT authentication and authorization for Spring Boot 3.5.x with token generation, refresh strategies, and role/permission-based access control. \n \n Covers token generation with JJWT, Bearer/cookie authentication, and stateless session management using Spring Security 6.x \n Supports database-backed and OAuth2 provider integration (Google, GitHub) with modern SecurityFilterChain configuration \n Includes refresh token rotation, token blacklisting, and key rotation strategies for production secu