jwt-attacks

jwt-attacks is a skill for Claude Code, Codex from blacklanternsecurity/red-run. It costs 18 tokens per session (4,338 once invoked), scanned A, original, GPL-3.0.

A security testing guide for finding weaknesses in JWTs, signed tokens commonly used to prove that a user is logged in.

In plain words
What is it for?
Authorized penetration testing of applications that use JSON Web Tokens for authentication.
Why use it?
It helps reveal when flawed token handling could let someone impersonate users or bypass access controls.

Skill for Claude CodeCodex

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

Good fit Authorized penetration testing of applications that use JSON Web Tokens for authentication.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/blacklanternsecurity/red-run/jwt-attacks
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 blacklanternsecurity/red-run --skill jwt-attacks
Clone the repo
git clone --depth 1 https://github.com/blacklanternsecurity/red-run

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 jwt-attacks

README.md
[![agentmods](https://agentmods.dev/badge/skills/blacklanternsecurity/red-run/jwt-attacks/github.svg)](https://agentmods.dev/skills/blacklanternsecurity/red-run/jwt-attacks)
Your own site
<a href="https://agentmods.dev/skills/blacklanternsecurity/red-run/jwt-attacks"><img src="https://agentmods.dev/badge/skills/blacklanternsecurity/red-run/jwt-attacks/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 jwt-attacks

Your own site · 80×15
<a href="https://agentmods.dev/skills/blacklanternsecurity/red-run/jwt-attacks"><img src="https://agentmods.dev/badge/skills/blacklanternsecurity/red-run/jwt-attacks.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 18 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,338 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 $0.00018 $0.04338
Opus 5 $0.00009 $0.02169
Sonnet 5 $0.00004 $0.00868
Haiku 4.5 $0.00002 $0.00434

Measured 5d ago against content hash 297954ed0607, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

jwt-attacks 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 5d 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 -s https://TARGET/.well-known/jwks.json
skills/web/jwt-attacks/SKILL.md · 522 lines

The source is not reproduced here

Licensed GPL-3.0

The repository is licensed GPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

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. 5d ago First seen · 522 lines · 18 tokens per session scan A 297954ed0607

Subscribe to this mod's changes

jwt-attacks is a skill published in the GitHub repository blacklanternsecurity/red-run (267 stars, last pushed 5mo ago), licensed GPL-3.0. It adds 18 tokens to every session and 4,338 once invoked, about $0.0001 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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