sast-jwt

sast-jwt is a skill for Claude Code, Codex from capture0x/YeepForge. It costs 123 tokens per session (5,862 once invoked), scanned A, original, no licence file.

A source-code review for insecure JSON Web Token (JWT) handling. JWTs are signed data commonly used to represent logged-in users; the review maps how tokens are created and checked, then looks for verification weaknesses.

In plain words
What is it for?
Use it to inspect JWT issuing and verification code for problems such as algorithm confusion or missing signature checks.
Why use it?
It helps find token checks that attackers might bypass or misuse to access accounts or protected actions. It also shows how token signing settings are used across the application.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/capture0x/yeepforge/sast-jwt
Any agent
npx skills add capture0x/YeepForge --skill sast-jwt
Clone the repo
git clone --depth 1 https://github.com/capture0x/YeepForge

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 sast-jwt

README.md
[![agentmods](https://agentmods.dev/badge/skills/capture0x/yeepforge/sast-jwt.svg)](https://agentmods.dev/skills/capture0x/yeepforge/sast-jwt)
Your own site
<a href="https://agentmods.dev/skills/capture0x/yeepforge/sast-jwt"><img src="https://agentmods.dev/badge/skills/capture0x/yeepforge/sast-jwt.svg" alt="Measured on agentmods" height="20"></a>
Per session 123 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,862 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
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 $0.00123 $0.05862
Opus 5 $0.00062 $0.02931
Sonnet 5 $0.00025 $0.01172
Haiku 4.5 $0.00012 $0.00586

Measured 4d ago against content hash 74f97c46964f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

sast-jwt 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 4d 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.

> [Proof-of-concept using jwt_tool, hashcat, or curl.
modules/sast_skills/sast-jwt/SKILL.md · 488 lines

The source is not reproduced here

A licence we could not identify

The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.

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. 4d ago First seen · 488 lines · 123 tokens per session scan A 74f97c46964f

Subscribe to this mod's changes

sast-jwt is a skill published in the GitHub repository capture0x/YeepForge (1 stars, last pushed 11d ago), with no licence file. It adds 123 tokens to every session and 5,862 once invoked, about $0.0006 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 2026-08-31.

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