security

security is a skill for Claude Code from avsm/ocaml-claude-marketplace. It costs 94 tokens per session (2,942 once invoked), scanned A, original, ISC.

A security-audit guide for OCaml libraries that studies known vulnerabilities, tests hostile input, and checks boundary cases. It focuses on parsers, encoders, integer handling, buffers, and related code.

In plain words
What is it for?
Use it to research comparable-library vulnerabilities, add regression and fuzz tests, audit parsers and encoders, and test empty, extreme, and overflowing inputs.
Why use it?
It helps reveal security bugs before release, especially bugs caused by malformed data, overflows, or unsafe assumptions. It also turns discovered issues into regression and fuzz tests.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the ocaml-dev plugin — 21 skills, 5 commands shipped together

Good fit Use it to research comparable-library vulnerabilities, add regression and fuzz tests, audit parsers and encoders, and test empty, extreme, and overflowing inputs.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/avsm/ocaml-claude-marketplace/security
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add avsm/ocaml-claude-marketplace --skill security
Clone the repo
git clone --depth 1 https://github.com/avsm/ocaml-claude-marketplace

Made for: Claude Code.

Or install ocaml-dev, the plugin that ships this one along with the rest of its 21 skills, 5 commands.

Wrote 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.

agentmods badge for security

README.md
[![agentmods](https://agentmods.dev/badge/skills/avsm/ocaml-claude-marketplace/security/github.svg)](https://agentmods.dev/skills/avsm/ocaml-claude-marketplace/security)
Your own site
<a href="https://agentmods.dev/skills/avsm/ocaml-claude-marketplace/security"><img src="https://agentmods.dev/badge/skills/avsm/ocaml-claude-marketplace/security/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.

agentmods 80×15 button for security

Your own site · 80×15
<a href="https://agentmods.dev/skills/avsm/ocaml-claude-marketplace/security"><img src="https://agentmods.dev/badge/skills/avsm/ocaml-claude-marketplace/security.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 94 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,942 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 2 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 2 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Data Exfiltration · line 55
    Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
    Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
  • medium Data Exfiltration · line 55
    Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
    Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00094 $0.02942
Opus 5 $0.00047 $0.01471
Sonnet 5 $0.00019 $0.00588
Haiku 4.5 $0.00009 $0.00294

Measured 12d ago against content hash 8c5adfc53f2f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

security scanned grade A with 2 findings 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 12d 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.

Sends data to an external URLlowData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

curl "https://api.osv.dev/v1/query" -d '{"package": {"name": "pillow", "ecosystem": "PyPI"}}'

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl "https://services.nvd.nist.gov/rest/json/cves/2.0?keywordSearch=libpng+buffer+overflow" | jq '.vulnerabilities[].cve.descriptions[0].value'
plugins/ocaml-dev/skills/security/SKILL.md · 348 lines

How it starts

The opening of the file, as written. The whole thing — 348 lines — stays where its author put it; the contents beside it link to each section on GitHub.

OCaml Security Audit

Systematic security hardening through vulnerability research, defensive coding, and comprehensive testing.

Core Philosophy

  1. Study the attacks first: Research CVEs in equivalent C/Rust/Go/Python libraries before writing tests
  2. Assume hostile input: Every parser, decoder, and protocol handler receives adversarial data
  3. Fail explicitly: Reject malformed input early with clear errors, never silently corrupt
  4. Test the boundaries: Edge cases at min/max values, empty input, and overflow points
  5. Defense in depth: Multiple validation layers, even when one seems sufficient

Workflow

Phase 1: CVE Research

Before writing any tests, research known vulnerabilities in equivalent implementations.

1. Identify comparable libraries:

OCaml library     → Research in
─────────────────────────────────────
PNG/image parser  → libpng, image-rs, Pillow
TLS/crypto        → OpenSSL, BoringSSL, rustls
HTTP parser       → http-parser, hyper, httptools
JSON parser       → json-c, serde_json, ujson
XML parser        → libxml2, quick-xml, defusedxml
Archive (zip/tar) → libarchive, zip-rs, tarfile
DNS resolver      → c-ares, trust-dns, dnspython
Compression       → zlib, miniz, flate2
YAML parser       → libyaml, serde_yaml, PyYAML
PDF parser        → poppler, pdf-rs, PyPDF2
ASN.1/X.509       → OpenSSL, ring, pyasn1

2. Search for CVEs:

# Search NVD database
curl "https://services.nvd.nist.gov/rest/json/cves/2.0?keywordSearch=libpng+buffer+overflow" | jq '.vulnerabilities[].cve.descriptions[0].value'

# Search CVE Details
# https://www.cvedetails.com/vulnerability-search.php

# Search GitHub Security Advisories
gh api graphql -f query='{ securityAdvisories(first:10, ecosystem:PIP, keyword:"pillow") { nodes { summary description severity } } }'

# Check OSV database
curl "https://api.osv.dev/v1/query" -d '{"package": {"name": "pillow", "ecosystem": "PyPI"}}'

3. Document findings - track CVEs and map to tests. See references/vulnerability-classes.md.

Read the full file on GitHub · 348 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

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.

  1. 12d ago First seen · 348 lines · 94 tokens per session scan A 8c5adfc53f2f

Subscribe to this mod's changes

security is a skill published in the GitHub repository avsm/ocaml-claude-marketplace (35 stars, last pushed 10d ago), licensed ISC. It adds 94 tokens to every session and 2,942 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 2 findings (sends data to an external url, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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