Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/marduk191/qwen3_mcpnpx agentmods add skills/marduk191/qwen3_mcp/ossfuzzWrote 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.
[](https://agentmods.dev/skills/marduk191/qwen3_mcp/ossfuzz)<a href="https://agentmods.dev/skills/marduk191/qwen3_mcp/ossfuzz"><img src="https://agentmods.dev/badge/skills/marduk191/qwen3_mcp/ossfuzz/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.
<a href="https://agentmods.dev/skills/marduk191/qwen3_mcp/ossfuzz"><img src="https://agentmods.dev/badge/skills/marduk191/qwen3_mcp/ossfuzz.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00029 | $0.03990 |
| Opus 5 | $0.00015 | $0.01995 |
| Sonnet 5 | $0.00006 | $0.00798 |
| Haiku 4.5 | $0.00003 | $0.00399 |
Grade A, and why
ossfuzz 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 9d 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.
| **Keep harnesses in separate repo** | Like [curl-fuzzer](https://github.com/curl/curl-fuzzer) - cleaner organization | This is a copy
98% identical to ossfuzz — 5 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.
How it starts
The opening of the file, as written. The whole thing — 427 lines — stays where its author put it; the contents beside it link to each section on GitHub.
OSS-Fuzz
OSS-Fuzz is an open-source project developed by Google that provides free distributed infrastructure for continuous fuzz testing. It streamlines the fuzzing process and facilitates simpler modifications. While only select projects are accepted into OSS-Fuzz, the project's core is open-source, allowing anyone to host their own instance for private projects.
Overview
OSS-Fuzz provides a simple CLI framework for building and starting harnesses or calculating their coverage. Additionally, OSS-Fuzz can be used as a service that hosts static web pages generated from fuzzing outputs such as coverage information.
Key Concepts
| Concept | Description |
|---|---|
| helper.py | CLI script for building images, building fuzzers, and running harnesses locally |
| Base Images | Hierarchical Docker images providing build dependencies and compilers |
| project.yaml | Configuration file defining project metadata for OSS-Fuzz enrollment |
| Dockerfile | Project-specific image with build dependencies |
| build.sh | Script that builds fuzzing harnesses for your project |
| Criticality Score | Metric used by OSS-Fuzz team to evaluate project acceptance |
When to Apply
Apply this technique when:
- Setting up continuous fuzzing for an open-source project
- Need distributed fuzzing infrastructure without managing servers
- Want coverage reports and bug tracking integrated with fuzzing
- Testing existing OSS-Fuzz harnesses locally
- Reproducing crashes from OSS-Fuzz bug reports
Skip this technique when:
- Project is closed-source (unless hosting your own OSS-Fuzz instance)
- Project doesn't meet OSS-Fuzz's criticality score threshold
- Need proprietary or specialized fuzzing infrastructure
- Fuzzing simple scripts that don't warrant infrastructure
Quick Reference
| Task | Command |
|---|---|
| Clone OSS-Fuzz | git clone https://github.com/google/oss-fuzz |
| Build project image | python3 infra/helper.py build_image --pull <project> |
| Build fuzzers with ASan | python3 infra/helper.py build_fuzzers --sanitizer=address <project> |
| Run specific harness | python3 infra/helper.py run_fuzzer <project> <harness> |
| Generate coverage report | python3 infra/helper.py coverage <project> |
| Check helper.py options | python3 infra/helper.py --help |
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.
- 9d ago First seen · 427 lines · 29 tokens per session scan A 5ba74748ddc7
ossfuzz is a skill published in the GitHub repository marduk191/qwen3_mcp (13 stars, last pushed 7mo ago), licensed MIT. It adds 29 tokens to every session and 3,990 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). It is 98% identical to ossfuzz, differing in 5 lines, and is treated as a copy.
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