JWT Algorithm Confusion Attack

JWT Algorithm Confusion Attack is a Quality skill for Claude Code, published by xalgord in xalgorix.

852 stars151 forkson xalgord/xalgorixAdded 2026/07/20+1% in starsRepository updated 2026/08/04

ai-agentai-securityautomationautonomous-pentestingbug-bountycybersecurityethical-hackinggolangpenetration-testingpentestpentesting-toolsreconsecuritysecurity-researchsecurity-toolstypescriptvulnerability-detectionvulnerability-scanner

Install in seconds

Install JWT Algorithm Confusion Attack

Copy JWT Algorithm Confusion Attack into your Claude Code skills folder. Run the command in your terminal, or review the source on GitHub before installing.

terminal

npx degit https://github.com/xalgorix/xalgorix/tree/main/internal/tools/skills/data/api-security/exploiting-jwt-algorithm-confusion-attack ~/.claude/skills/exploiting-jwt-algorithm-confusion-attack

Requires Node.js. Downloads this skill only — not the rest of the repository — into your Claude Code skills folder.

Without Node.js

git clone https://github.com/xalgorix/xalgorix.git

Clones the whole repository, then copy the skill’s own directory into your skills folder yourself.

In this catalog

Source file: internal/tools/skills/data/api-security/exploiting-jwt-algorithm-confusion-attack/SKILL.md in xalgord/xalgorix
Installs to: ~/.claude/skills/exploiting-jwt-algorithm-confusion-attack
Collection: One of 51 skills cataloged from this repository
Category: Quality — 1897 skills

What JWT Algorithm Confusion Attack does

Exploits JWT algorithm confusion vulnerabilities where the server's token verification library accepts the token's specified algorithm, allowing attackers to forge tokens and bypass authentication. Useful for authorized security testing of JWT-based APIs.

JWT Algorithm Confusion Attack is cataloged under Quality on DirSkills. JWT Algorithm Confusion Attack comes from a repository tagged ai-agent, ai-security, automation, autonomous-pentesting and bug-bounty.

Documentation

README

Excerpt

Exploiting JWT Algorithm Confusion Attack

When to Use

Testing APIs that use RS256 (asymmetric) JWT tokens for authentication to check for algorithm downgrade to HS256
Assessing JWT implementations for alg:none bypass where the server skips signature verification
Evaluating JWT libraries for key confusion vulnerabilities where the public key is used as HMAC secret
Testing kid (Key ID), jku (JWK Set URL), and x5u (X.509 URL) header parameters for injection
Validating that the API server enforces a specific algorithm and does not trust the JWT header

Do not use without written authorization. JWT exploitation can lead to authentication bypass and account takeover.

Most Often Missed & How to Confirm

This is the opening of the README. Read the full README on GitHub.

Frequently asked about JWT Algorithm Confusion Attack

What else does xalgord publish alongside JWT Algorithm Confusion Attack?
JWT Algorithm Confusion Attack is one of 51 skills that DirSkills catalogs from xalgord/xalgorix, the repository it ships in. Its siblings there include AFL++ Fuzzing, AI Security Guardrails and AI-Assisted Vulnerability Discovery. Each one is a separate skill with its own page in this directory, installs the same way JWT Algorithm Confusion Attack does, and is maintained by xalgord in that same repository. The rest of the collection is listed on the xalgord/xalgorix page.
How does JWT Algorithm Confusion Attack compare to other Quality skills?
JWT Algorithm Confusion Attack ranks #931 by stars among the 1897 Quality skills in this catalog. The most-starred ones next to it are Benchmark, Benchmark Optimization Loop and API Design Patterns. DirSkills ranks by the star count of the repository each skill ships in, so that order reflects how popular those repositories are rather than any review of JWT Algorithm Confusion Attack against them. Open each page to compare what they document and how they install.