testing-for-json-web-token-vulnerabilities

testing-for-json-web-token-vulnerabilities is a skill for Claude Code, Codex from Njones17/AI-agent-master-cyber-skills-list. It costs 39 tokens per session (2,197 once invoked), scanned A, original, no licence file.

A web-security testing guide for finding weaknesses in JSON Web Tokens (JWTs), signed data commonly used to prove a user's identity.

In plain words
What is it for?
Use it to assess JWT signing, algorithm handling, secret strength, and parameters such as alg and kid.
Why use it?
It helps uncover authentication bypasses and privilege escalation caused by unsafe algorithms, weak secrets, or injectable token parameters.

Skill for Claude CodeCodex

Which agent this was written for is unclear — body not stored (licence); the path alone says nothing.

Good fit Use it to assess JWT signing, algorithm handling, secret strength, and parameters such as alg and kid.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/njones17/ai-agent-master-cyber-skills-list/testing-for-json-web-token-vulnerabilities
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add Njones17/AI-agent-master-cyber-skills-list --skill testing-for-json-web-token-vulnerabilities
Clone the repo
git clone --depth 1 https://github.com/Njones17/AI-agent-master-cyber-skills-list

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for testing-for-json-web-token-vulnerabilities

README.md
[![agentmods](https://agentmods.dev/badge/skills/njones17/ai-agent-master-cyber-skills-list/testing-for-json-web-token-vulnerabilities/github.svg)](https://agentmods.dev/skills/njones17/ai-agent-master-cyber-skills-list/testing-for-json-web-token-vulnerabilities)
Your own site
<a href="https://agentmods.dev/skills/njones17/ai-agent-master-cyber-skills-list/testing-for-json-web-token-vulnerabilities"><img src="https://agentmods.dev/badge/skills/njones17/ai-agent-master-cyber-skills-list/testing-for-json-web-token-vulnerabilities/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for testing-for-json-web-token-vulnerabilities

Your own site · 80×15
<a href="https://agentmods.dev/skills/njones17/ai-agent-master-cyber-skills-list/testing-for-json-web-token-vulnerabilities"><img src="https://agentmods.dev/badge/skills/njones17/ai-agent-master-cyber-skills-list/testing-for-json-web-token-vulnerabilities.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,197 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00039 $0.02197
Opus 5 $0.00019 $0.01099
Sonnet 5 $0.00008 $0.00439
Haiku 4.5 $0.00004 $0.00220

Measured 8d ago against content hash da0ab535f70d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

testing-for-json-web-token-vulnerabilities scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -H "Authorization: Bearer <FORGED_TOKEN>" http://target.com/api/admin
skills/application-security/testing-for-json-web-token-vulnerabilities/SKILL.md · 222 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 8d ago First seen · 222 lines · 39 tokens per session scan A da0ab535f70d

Subscribe to this mod's changes

testing-for-json-web-token-vulnerabilities is a skill published in the GitHub repository Njones17/AI-agent-master-cyber-skills-list (21 stars, last pushed 6mo ago), with no licence file. It adds 39 tokens to every session and 2,197 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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