libfuzzer SKILL.md skillA
libfuzzer from trailofbits/skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add trailofbits/skills/libfuzzer@git:20260826.3deb39ePins git:20260826.3deb39e in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- trailofbits/skills
- Path
plugins/testing-handbook-skills/skills/libfuzzer/SKILL.md- Versions recorded
- 2
- Latest version
- git:20260826.3deb39e, committed Aug 26, 2026
- First version recorded
- Jan 14, 2026
- Size
- 24,234 bytes
- Repository stars
- 8,043
- License
- CC-BY-SA-4.0
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.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# libFuzzer libFuzzer is an in-process, coverage-guided fuzzer that is part of the LLVM project. It's the recommended starting point for fuzzing C/C++ projects due to its simplicity and integration with the LLVM toolchain. While libFuzzer has been in maintenance-only mode since late 2022, it is easier to install and use than its alternatives, has wide support, and will be maintained for the foreseeable future. ## When to Use | Fuzzer | Best For | Complexity | |--------|----------|------------| | libFuzzer | Quick setup, single-project fuzzing | Low | | AFL++ | Multi-core fuzzing, diverse mutations | Medium | | LibAFL | Custom fuzzers, research projects | High | | Honggfuzz | Hardware-based coverage | Medium | **Choose libFuzzer when:** - You need a simple, quick setup for C/C++ code - Project uses Clang for compilation - Single-core fuzzing is sufficient initially - Transitioning to AFL++ later is an option (harnesses are compatible) **Note:** Fuzzing harnesses written for libFuzzer are compatible with AFL++, making it easy to transition if you need more advanced features like better multi-core support. ## Quick Start ```c++ #include <stdint.h> #include <stddef.h> …
Read the whole file at its exact version.
How to install
mdr add trailofbits/skills/libfuzzer@sha256:56b2c68b193f7fedThe line at the top of this page pins the label git:20260826.3deb39e, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_caorv6skewd4bp3m)
3 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 2 versions of this file, between Jan 14, 2026 and Aug 26, 2026, about one every 224 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260826.3deb39e latest | 2026-08-26 | 3deb39e | 24,234 B | A | view · diff |
| git:20260114.695119c | 2026-01-14 | 695119c | 23,925 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (24234 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
trailofbits/skills · 8,043 stars · license CC-BY-SA-4.0 · pushed 2026-11-06 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_caorv6skewd4bp3m GET https://markdownregistry.com/api/v1/resolve?ref=trailofbits/skills/libfuzzer GET https://markdownregistry.com/api/v1/blob/56b2c68b193f7fed4ae00ade6c6395196d44612d140ad51de43d150404dde2eb
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.
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