libfuzzer

Automate coverage-guided fuzzing of C/C++ code with libFuzzer and Clang.

1|Updated Jan 31, 2026

Search Tags:#security #c++#llvm #fuzzing #libfuzzer #bug finding

Ready to run

npx skills add https://github.com/allanninal/claude-code-skills --skill libfuzzer-allanninal

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: libfuzzer
Source: https://github.com/allanninal/claude-code-skills/tree/main/skills/libfuzzer
Command: npx skills add https://github.com/allanninal/claude-code-skills --skill libfuzzer-allanninal

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

This Skill helps you discover bugs and security vulnerabilities in C/C++ code by automatically generating diverse inputs and testing them against your program.

Core Features & Use Cases

Coverage-Guided Fuzzing: Efficiently explores code paths using LLVM's instrumentation.
Integration with Clang: Seamlessly works with the Clang compiler toolchain.
Use Case: You have a C library that parses network protocols. Use this Skill to fuzz the parsing function, automatically finding malformed inputs that cause crashes or security issues.

Quick Start

Use the libfuzzer skill to fuzz the 'my_target_function' in 'target.cc' using the harness in 'harness.cc'.

Frequently Asked Questions about libfuzzer

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I find bugs in C++ code using coverage-guided fuzzing?▼

Coverage-guided fuzzing finds bugs in C++ code by using LLVM instrumentation to automatically generate diverse inputs and test them against your program to discover crashes and security vulnerabilities.

How do I set up a fuzzing harness for a C library?▼

To set up fuzzing for a C library, compile the project with Clang and use a harness file to target specific functions, allowing the in-process fuzzer to efficiently explore code paths and test malformed inputs.

Does libFuzzer work with the Clang compiler toolchain?▼

Yes, libFuzzer is an in-process, coverage-guided fuzzer integrated directly with the LLVM toolchain, requiring Clang to compile C/C++ projects and enable efficient code path instrumentation.

Can I migrate existing AFL++ harnesses to libFuzzer?▼

Yes, libFuzzer offers compatibility with AFL++ harnesses, allowing you to easily migrate existing fuzzing setups and quickly start single-project fuzzing without rewriting your testing logic.

What is the best way to fuzz a network protocol parser in C?▼

The best way to fuzz a network protocol parser in C is to use an in-process, coverage-guided fuzzer to automatically generate malformed inputs, efficiently triggering crashes and security issues in the parsing function.