fuzzing-dictionary

fuzzing-dictionary is a skill for Claude Code from marduk191/qwen3_mcp. It costs 32 tokens per session (2,372 once invoked), scanned A, a copy of fuzzing-dictionary, MIT.

A dictionary of meaningful words, symbols, byte sequences, or commands that a fuzzer can insert into generated test inputs. A fuzzer automatically creates many unusual inputs to find bugs in parsers, protocols, and file-format code.

In plain words
What is it for?
Use it when fuzzing formats such as JSON or XML, network protocols such as HTTP or DNS, or custom parsers with known keywords, magic values, and commands.
Why use it?
Random input changes often fail early validation and never reach deeper code. Domain-specific tokens help the fuzzer explore behavior that blind mutation may miss.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the testing-handbook-skills plugin — 15 skills shipped together

Good fit Use it when fuzzing formats such as JSON or XML, network protocols such as HTTP or DNS, or custom parsers with known keywords, magic values, and commands.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/marduk191/qwen3_mcp/fuzzing-dictionary
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 marduk191/qwen3_mcp --skill fuzzing-dictionary
Clone the repo
git clone --depth 1 https://github.com/marduk191/qwen3_mcp

Made for: Claude Code.

Or install testing-handbook-skills, the plugin that ships this one along with the rest of its 15 skills.

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 fuzzing-dictionary

README.md
[![agentmods](https://agentmods.dev/badge/skills/marduk191/qwen3_mcp/fuzzing-dictionary/github.svg)](https://agentmods.dev/skills/marduk191/qwen3_mcp/fuzzing-dictionary)
Your own site
<a href="https://agentmods.dev/skills/marduk191/qwen3_mcp/fuzzing-dictionary"><img src="https://agentmods.dev/badge/skills/marduk191/qwen3_mcp/fuzzing-dictionary/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 fuzzing-dictionary

Your own site · 80×15
<a href="https://agentmods.dev/skills/marduk191/qwen3_mcp/fuzzing-dictionary"><img src="https://agentmods.dev/badge/skills/marduk191/qwen3_mcp/fuzzing-dictionary.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 32 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,372 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 94% 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 $0.00032 $0.02372
Opus 5 $0.00016 $0.01186
Sonnet 5 $0.00006 $0.00474
Haiku 4.5 $0.00003 $0.00237

Measured 10d ago against content hash 3247064b931f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

fuzzing-dictionary 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 10d 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.

man curl | grep -oP '^\s*(--|-)\K\S+' | sed 's/[,.]$//' | sed 's/^/"&/; s/$/&"/' | sort -u > man.dict
Origin

This is a copy

94% identical to fuzzing-dictionary — 5 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/testing-handbook-skills/skills/fuzzing-dictionary/SKILL.md · 298 lines

How it starts

The opening of the file, as written. The whole thing — 298 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Fuzzing Dictionary

A fuzzing dictionary provides domain-specific tokens to guide the fuzzer toward interesting inputs. Instead of purely random mutations, the fuzzer incorporates known keywords, magic numbers, protocol commands, and format-specific strings that are more likely to reach deeper code paths in parsers, protocol handlers, and file format processors.

Overview

Dictionaries are text files containing quoted strings that represent meaningful tokens for your target. They help fuzzers bypass early validation checks and explore code paths that would be difficult to reach through blind mutation alone.

Key Concepts

Concept Description
Dictionary Entry A quoted string (e.g., "keyword") or key-value pair (e.g., kw="value")
Hex Escapes Byte sequences like "\xF7\xF8" for non-printable characters
Token Injection Fuzzer inserts dictionary entries into generated inputs
Cross-Fuzzer Format Dictionary files work with libFuzzer, AFL++, and cargo-fuzz

When to Apply

Apply this technique when:

  • Fuzzing parsers (JSON, XML, config files)
  • Fuzzing protocol implementations (HTTP, DNS, custom protocols)
  • Fuzzing file format handlers (PNG, PDF, media codecs)
  • Coverage plateaus early without reaching deeper logic
  • Target code checks for specific keywords or magic values

Skip this technique when:

  • Fuzzing pure algorithms without format expectations
  • Target has no keyword-based parsing
  • Corpus already achieves high coverage

Quick Reference

Task Command/Pattern
Use with libFuzzer ./fuzz -dict=./dictionary.dict ...
Use with AFL++ afl-fuzz -x ./dictionary.dict ...
Use with cargo-fuzz cargo fuzz run fuzz_target -- -dict=./dictionary.dict
Extract from header grep -o '".*"' header.h > header.dict
Generate from binary strings ./binary | sed 's/^/"&/; s/$/&"/' > strings.dict

Step-by-Step

Step 1: Create Dictionary File

Read the full file on GitHub · 298 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. 10d ago First seen · 298 lines · 32 tokens per session scan A 3247064b931f

Subscribe to this mod's changes

fuzzing-dictionary is a skill published in the GitHub repository marduk191/qwen3_mcp (13 stars, last pushed 7mo ago), licensed MIT. It adds 32 tokens to every session and 2,372 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 94% identical to fuzzing-dictionary, differing in 5 lines, and is treated as a copy.

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