libfuzzer

Automates libFuzzer coverage-guided fuzzing of C/C++ codebases with AddressSanitizer and LLVM toolchain instrumentation.

Updated Feb 24, 2026

Search Tags:#debugging #security #vulnerability #c++#llvm #fuzzing

Ready to run

npx skills add https://github.com/ofelixdev/cc-kit --skill libfuzzer-ofelixdev

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: libfuzzer
Source: https://github.com/ofelixdev/cc-kit/tree/main/template/skills/libfuzzer
Command: npx skills add https://github.com/ofelixdev/cc-kit --skill libfuzzer-ofelixdev

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

This Skill helps you find bugs and security vulnerabilities in C/C++ code by automatically generating diverse inputs to test your program's behavior.

Core Features & Use Cases

Coverage-guided fuzzing: Efficiently explores code paths using LLVM's instrumentation.
Easy integration: Works seamlessly with Clang and the LLVM toolchain.
Use Case: You have a C library for parsing image files. Use this Skill to fuzz the parsing function, automatically discovering malformed inputs that could lead to crashes or security exploits.

Quick Start

Use the libfuzzer skill to fuzz the provided C++ harness file 'harness.cc' and target 'target.cc'.

Frequently Asked Questions about libfuzzer

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

FAQPage Schema

How do I fuzz C/C++ code to find security vulnerabilities?▼

Fuzzing C/C++ code automates bug discovery by generating diverse test cases to exercise code paths. This process uses LLVM's coverage-guided instrumentation to detect memory errors and analyze code behavior.

What libraries or compilers do I need for coverage-guided fuzzing?▼

Coverage-guided fuzzing requires the Clang compiler and the LLVM toolchain. These tools provide the necessary instrumentation to track code paths and execute in-process fuzzing targets.

How does AddressSanitizer detect memory errors during fuzzing?▼

AddressSanitizer detects memory errors during fuzzing by integrating with the LLVM toolchain to monitor memory access. It automatically identifies malformed inputs that cause crashes or security exploits.

What is the best way to test a C library for malformed input crashes?▼

The best way to test for malformed input crashes is using an in-process, coverage-guided fuzzer. It automatically generates diverse inputs to exercise parsing functions, exposing potential vulnerabilities.

Can I use this for fuzzing an image parsing function in C++?▼

Yes, you can fuzz image parsing functions by providing a C++ harness file and target code. The fuzzer automatically generates malformed inputs to discover crashes and security vulnerabilities.

Why does fuzzing require LLVM and Clang integration?▼

Fuzzing requires LLVM and Clang integration because it relies on in-process, coverage-guided instrumentation. Clang compiles the code with specific instrumentation that maps and explores code paths efficiently.