aflpp

aflpp is a skill for Claude Code, Codex from onfire7777/universal-ai-skills-library. It costs 33 tokens per session (4,618 once invoked), scanned A, a copy of aflpp, MIT.

AFL++, a tool that repeatedly feeds modified inputs to C and C++ programs to find crashes and other unexpected behaviour; this testing method is called fuzzing. It is designed for fuzzing across multiple processor cores.

In plain words
What is it for?
Use it for multi-core fuzz testing of C or C++ projects, especially when the code can be compiled with Clang or GCC.
Why use it?
It helps find bugs that are difficult to anticipate with a fixed set of hand-written tests and can run many test cases in parallel.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: positional $N argument.

Good fit Use it for multi-core fuzz testing of C or C++ projects, especially when the code can be compiled with Clang or GCC.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/onfire7777/universal-ai-skills-library/aflpp
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 onfire7777/universal-ai-skills-library --skill aflpp
Clone the repo
git clone --depth 1 https://github.com/onfire7777/universal-ai-skills-library

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 aflpp

README.md
[![agentmods](https://agentmods.dev/badge/skills/onfire7777/universal-ai-skills-library/aflpp/github.svg)](https://agentmods.dev/skills/onfire7777/universal-ai-skills-library/aflpp)
Your own site
<a href="https://agentmods.dev/skills/onfire7777/universal-ai-skills-library/aflpp"><img src="https://agentmods.dev/badge/skills/onfire7777/universal-ai-skills-library/aflpp/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 aflpp

Your own site · 80×15
<a href="https://agentmods.dev/skills/onfire7777/universal-ai-skills-library/aflpp"><img src="https://agentmods.dev/badge/skills/onfire7777/universal-ai-skills-library/aflpp.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,618 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 86% 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 $0.00033 $0.04618
Opus 5 $0.00016 $0.02309
Sonnet 5 $0.00007 $0.00924
Haiku 4.5 $0.00003 $0.00462

Measured 12d ago against content hash 9a6da5a4e897, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

aflpp 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 12d 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 -O https://raw.githubusercontent.com/AFLplusplus/AFLplusplus/stable/utils/argv_fuzzing/argv-fuzz-inl.h
Origin

This is a copy

86% identical to aflpp — 75 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/aflpp/SKILL.md · 572 lines

How it starts

The opening of the file, as written. The whole thing — 572 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AFL++

AFL++ is a fork of the original AFL fuzzer that offers better fuzzing performance and more advanced features while maintaining stability. A major benefit over libFuzzer is that AFL++ has stable support for running fuzzing campaigns on multiple cores, making it ideal for large-scale fuzzing efforts.

When to Use

Fuzzer Best For Complexity
AFL++ Multi-core fuzzing, diverse mutations, mature projects Medium
libFuzzer Quick setup, single-threaded, simple harnesses Low
LibAFL Custom fuzzers, research, advanced use cases High

Choose AFL++ when:

  • You need multi-core fuzzing to maximize throughput
  • Your project can be compiled with Clang or GCC
  • You want diverse mutation strategies and mature tooling
  • libFuzzer has plateaued and you need more coverage
  • You're fuzzing production codebases that benefit from parallel execution

Quick Start

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
    // Call your code with fuzzer-provided data
    check_buf((char*)data, size);
    return 0;
}

Compile and run:

# Setup AFL++ wrapper script first (see Installation)
./afl++ docker afl-clang-fast++ -DNO_MAIN=1 -O2 -fsanitize=fuzzer harness.cc main.cc -o fuzz
mkdir seeds && echo "aaaa" > seeds/minimal_seed
./afl++ docker afl-fuzz -i seeds -o out -- ./fuzz

Installation

AFL++ has many dependencies including LLVM, Python, and Rust. We recommend using a current Debian or Ubuntu distribution for fuzzing with AFL++.

Method When to Use Supported Compilers
Ubuntu/Debian repos Recent Ubuntu, basic features only Ubuntu 23.10: Clang 14 & GCC 13Debian 12: Clang 14 & GCC 12
Docker (from Docker Hub) Specific AFL++ version, Apple Silicon support As of 4.35c: Clang 19 & GCC 11
Docker (from source) Test unreleased features, apply patches Configurable in Dockerfile
From source Avoid Docker, need specific patches Adjustable via LLVM_CONFIG env var

Read the full file on GitHub · 572 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. 12d ago First seen · 572 lines · 33 tokens per session scan A 9a6da5a4e897

Subscribe to this mod's changes

aflpp is a skill published in the GitHub repository onfire7777/universal-ai-skills-library (16 stars, last pushed yesterday), licensed MIT. It adds 33 tokens to every session and 4,618 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 86% identical to aflpp, differing in 75 lines, and is treated as a copy.

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