api-fuzzing-bug-bounty

api-fuzzing-bug-bounty is a skill for Claude Code, Codex from tmolavi/mcp-agent-skills-hub. It costs 48 tokens per session (2,786 once invoked), scanned A, a copy of api-fuzzing-bug-bounty, MIT.

A guide to testing REST, SOAP, and GraphQL APIs for security weaknesses during authorized bug-bounty or penetration-testing work.

In plain words
What is it for?
Use it to discover endpoints, test authentication and permissions, fuzz inputs, and document verified API vulnerabilities.
Why use it?
It provides a structured way to look for problems such as authentication bypasses, IDOR, injection, and unauthorized data access.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to discover endpoints, test authentication and permissions, fuzz inputs, and document verified API vulnerabilities.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/tmolavi/mcp-agent-skills-hub/api-fuzzing-bug-bounty
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 tmolavi/mcp-agent-skills-hub --skill api-fuzzing-bug-bounty
Clone the repo
git clone --depth 1 https://github.com/tmolavi/mcp-agent-skills-hub

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 api-fuzzing-bug-bounty

README.md
[![agentmods](https://agentmods.dev/badge/skills/tmolavi/mcp-agent-skills-hub/api-fuzzing-bug-bounty/github.svg)](https://agentmods.dev/skills/tmolavi/mcp-agent-skills-hub/api-fuzzing-bug-bounty)
Your own site
<a href="https://agentmods.dev/skills/tmolavi/mcp-agent-skills-hub/api-fuzzing-bug-bounty"><img src="https://agentmods.dev/badge/skills/tmolavi/mcp-agent-skills-hub/api-fuzzing-bug-bounty/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 api-fuzzing-bug-bounty

Your own site · 80×15
<a href="https://agentmods.dev/skills/tmolavi/mcp-agent-skills-hub/api-fuzzing-bug-bounty"><img src="https://agentmods.dev/badge/skills/tmolavi/mcp-agent-skills-hub/api-fuzzing-bug-bounty.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,786 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 92% copy Near-identical to another mod 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 $0.00048 $0.02786
Opus 5 $0.00024 $0.01393
Sonnet 5 $0.00010 $0.00557
Haiku 4.5 $0.00005 $0.00279

Measured 11d ago against content hash 585145141d7d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

api-fuzzing-bug-bounty 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 11d 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 -X POST https://target.com/graphql \
Origin

This is a copy

92% identical to api-fuzzing-bug-bounty — 14 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/api-fuzzing-bug-bounty/SKILL.md · 440 lines

How it starts

The opening of the file, as written. The whole thing — 440 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AUTHORIZED USE ONLY: Use this skill only for authorized security assessments, defensive validation, or controlled educational environments.

API Fuzzing for Bug Bounty

Purpose

Provide comprehensive techniques for testing REST, SOAP, and GraphQL APIs during bug bounty hunting and penetration testing engagements. Covers vulnerability discovery, authentication bypass, IDOR exploitation, and API-specific attack vectors.

Inputs/Prerequisites

  • Burp Suite or similar proxy tool
  • API wordlists (SecLists, api_wordlist)
  • Understanding of REST/GraphQL/SOAP protocols
  • Python for scripting
  • Target API endpoints and documentation (if available)

Outputs/Deliverables

  • Identified API vulnerabilities
  • IDOR exploitation proofs
  • Authentication bypass techniques
  • SQL injection points
  • Unauthorized data access documentation

API Types Overview

Type Protocol Data Format Structure
SOAP HTTP XML Header + Body
REST HTTP JSON/XML/URL Defined endpoints
GraphQL HTTP Custom Query Single endpoint

Core Workflow

Step 1: API Reconnaissance

Identify API type and enumerate endpoints:

# Check for Swagger/OpenAPI documentation
/swagger.json
/openapi.json
/api-docs
/v1/api-docs
/swagger-ui.html

# Use Kiterunner for API discovery
kr scan https://target.com -w routes-large.kite

# Extract paths from Swagger
python3 json2paths.py swagger.json

Step 2: Authentication Testing

# Test different login paths
/api/mobile/login
/api/v3/login
/api/magic_link
/api/admin/login

# Check rate limiting on auth endpoints
# If no rate limit → brute force possible

# Test mobile vs web API separately
# Don't assume same security controls

Step 3: IDOR Testing

Insecure Direct Object Reference is the most common API vulnerability:

# Basic IDOR
GET /api/users/1234 → GET /api/users/1235

# Even if ID is email-based, try numeric
/?user_id=111 instead of /[email protected]

# Test /me/orders vs /user/654321/orders

Read the full file on GitHub · 440 lines

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. 11d ago First seen · 440 lines · 48 tokens per session scan A 585145141d7d

Subscribe to this mod's changes

api-fuzzing-bug-bounty is a skill published in the GitHub repository tmolavi/mcp-agent-skills-hub (8 stars, last pushed 16d ago), licensed MIT. It adds 48 tokens to every session and 2,786 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). It is 92% identical to api-fuzzing-bug-bounty, differing in 14 lines, and is treated as a copy.

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