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jwt-attack

Audits and exploits JSON Web Tokens to identify authentication bypass vulnerabilities.

3|1|Updated Jul 2, 2026
Search Tags:#security#authentication#api#jwt#pentest#recon
One-click install
npx skills add https://github.com/EntroVyx/hermes-agent-offsec --skill jwt-attack-entrovyx
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: jwt-attack
Source: https://github.com/EntroVyx/hermes-agent-offsec/tree/main/skills/offsec/recon/jwt-attack
Command: npx skills add https://github.com/EntroVyx/hermes-agent-offsec --skill jwt-attack-entrovyx

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill requires curl, nmap, python3, masscan, subfinder, httpx, nuclei.

What problem does it solve?

This skill addresses the complexity of auditing JSON Web Tokens (JWT) by automating the identification of weak configurations, algorithm confusion, and insecure implementation patterns that lead to unauthorized access.

Core Features & Use Cases

  • Token Analysis: Decodes and validates JWT structures, checking for expiration and payload integrity.
  • Exploitation Modules: Automates common attacks including alg:none, RS256 to HS256 key confusion, and kid injection.
  • Use Case: During a security assessment of an API using Bearer authentication, use this skill to quickly determine if the server is vulnerable to token forgery or if hardcoded secrets can be brute-forced.

Quick Start

Use the jwt-attack skill to decode the provided token and check for potential algorithm confusion vulnerabilities.

Frequently Asked Questions about jwt-attack

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I test JWT authentication bypass vulnerabilities in web applications?▼

You can test JWT authentication bypass by decoding token structures and automating cryptographic attacks like alg:none, RS256 to HS256 key confusion, and kid injection to identify unauthorized access flaws.

What is an RS256 to HS256 key confusion attack on JSON Web Tokens?▼

An RS256 to HS256 key confusion attack exploits weak JWT configurations by forcing the server to validate the token using a symmetric algorithm with the public key, allowing token forgery and authentication bypass.

Can I brute force hardcoded JWT secrets during an API security assessment?▼

Yes, you can brute force hardcoded JWT secrets using standard wordlists and curl during an API security assessment to determine if Bearer authentication tokens can be forged.

Do I need python3 and curl to perform cryptographic attacks on JSON Web Tokens?▼

Yes, you need python3 and curl along with standard wordlists to execute cryptographic attacks and header manipulation when auditing JSON Web Tokens for weak configurations.

What is the best way to automate alg:none and kid injection attacks for pentesting?▼

The best way to automate alg:none and kid injection attacks is using a tool that decodes JWT payload integrity and checks for algorithm confusion vulnerabilities to expose unauthorized access risks.

Why does my JWT exploitation fail when checking payload integrity and expiration?▼

JWT exploitation may fail if the token structure is invalid or if the server enforces strict expiration validation, preventing cryptographic attacks and header manipulation from succeeding.

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