# libfuzzer

> Sets up and runs libFuzzer, the coverage-guided fuzzer built into LLVM, on C/C++ code that compiles with Clang.

Sets up and runs libFuzzer, the coverage-guided fuzzer built into LLVM, on C/C++ code that compiles with Clang. Covers harness structure, -fsanitize=fuzzer builds, corpus and dictionary management, sanitizer integration, and campaign triage. Use when writing or debugging an LLVMFuzzerTestOneInput harness, starting fuzzing on a C/C++ library, choosing between libFuzzer and AFL++, or working out why a libFuzzer run finds nothing.

- Type: Skill
- Made by: trailofbits
- Category: Developer tools
- Formats: Skills
- Version: 6ab7664
- Source: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills/skills/libfuzzer
- Page: https://pluginboard.ai/skills/libfuzzer-trailofbits

## Works with

- ChatGPT
- Claude
- Gemini
- GitHub Copilot
- Cursor
- Claude Code
- Codex
- Antigravity
- Gemini CLI
- Replit
- OpenClaw
- OpenCode
- Hermes Agent

## Install

### ChatGPT

In ChatGPT: Download the libfuzzer folder and zip it, then Plugins → Skills → Create → Upload from your computer. Business and Enterprise plans.

View the folder on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills/skills/libfuzzer

### Claude

In Claude (web or desktop): Download the libfuzzer folder and zip the folder itself, then upload it in Customize → Skills.

View the folder on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills/skills/libfuzzer

### Gemini

In Gemini: Download the libfuzzer folder, then at gemini.google.com click Customize → Skills → Create → Upload and pick the folder (or a .zip of it).

View the folder on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills/skills/libfuzzer

### GitHub Copilot

Run in your terminal:

```shell
npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.copilot/skills/libfuzzer
```

View the folder on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills/skills/libfuzzer

### Cursor

Run in your terminal:

```shell
npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.cursor/skills/libfuzzer
```

View the folder on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills/skills/libfuzzer

### Claude Code

Run in your terminal:

```shell
npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.claude/skills/libfuzzer
```

View the folder on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills/skills/libfuzzer

Or all of Testing Handbook Skills, in Claude Code:

```text
/plugin marketplace add trailofbits/skills
/plugin install testing-handbook-skills@trailofbits
```

### Codex

Run in your terminal:

```shell
npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.agents/skills/libfuzzer
```

View the folder on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills/skills/libfuzzer

### Antigravity

In Antigravity: Copy the libfuzzer folder into ~/.gemini/config/skills (Antigravity app and IDE) or ~/.gemini/antigravity-cli/skills (Antigravity CLI).

View the folder on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills/skills/libfuzzer

### Gemini CLI

Run in your terminal:

```shell
npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.gemini/skills/libfuzzer
```

View the folder on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills/skills/libfuzzer

### Replit

Run in your terminal:

```shell
npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer .agents/skills/libfuzzer
```

View the folder on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills/skills/libfuzzer

### OpenClaw

Run in your terminal:

```shell
npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.openclaw/skills/libfuzzer
```

View the folder on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills/skills/libfuzzer

### OpenCode

Run in your terminal:

```shell
npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.config/opencode/skills/libfuzzer
```

View the folder on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills/skills/libfuzzer

### Hermes Agent

Run in your terminal:

```shell
npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.hermes/skills/libfuzzer
```

View the folder on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills/skills/libfuzzer

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From Pluginboard (https://pluginboard.ai).