C31-review-security

C31-review-security is a skill for Claude Code, Codex from ChianW/C31. It costs 67 tokens per session (752 once invoked), scanned A, original, MIT.

A read-only security reviewer for changes involving authentication, web endpoints, user input, or permissions.

In plain words
What is it for?
Use it to inspect diffs and endpoint handlers for security weaknesses, including unsafe input handling, privilege problems, insecure settings, and sensitive information exposure.
Why use it?
It helps identify exploitable problems such as injection, cross-site scripting, authentication bypasses, exposed secrets, missing access checks, and accidental data leaks before code is merged.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions subagents.

Good fit Use it to inspect diffs and endpoint handlers for security weaknesses, including unsafe input handling, privilege problems, insecure settings, and sensitive information exposure.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/chianw/c31/c31-review-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 ChianW/C31 --skill c31-review-security
Clone the repo
git clone --depth 1 https://github.com/ChianW/C31

Made for: Claude Code, Codex.

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 C31-review-security

README.md
[![agentmods](https://agentmods.dev/badge/skills/chianw/c31/c31-review-security/github.svg)](https://agentmods.dev/skills/chianw/c31/c31-review-security)
Your own site
<a href="https://agentmods.dev/skills/chianw/c31/c31-review-security"><img src="https://agentmods.dev/badge/skills/chianw/c31/c31-review-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 C31-review-security

Your own site · 80×15
<a href="https://agentmods.dev/skills/chianw/c31/c31-review-security"><img src="https://agentmods.dev/badge/skills/chianw/c31/c31-review-security.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 752 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
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 $0.00067 $0.00752
Opus 5 $0.00034 $0.00376
Sonnet 5 $0.00013 $0.00150
Haiku 4.5 $0.00007 $0.00075

Measured 10d ago against content hash 59367ef81dd0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

C31-review-security 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 10d 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.

- `confidence`: 100 = I can write a curl to exploit this; 75 = clear vulnerable pattern; 50 = plausible with specific input; 25 = suspicious but unlikely.
skills/review/C31-review-security/SKILL.md · 83 lines

How it starts

The opening of the file, as written. The whole thing — 83 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Multilingual Triggers

Language Trigger phrases
EN C31-review-security
ZH 安全审查, 安全检查
JA セキュリティレビュー, 脆弱性チェック

Output language: Respond automatically in the user's conversation language.

C31 Review — Security

Focus

  • Injection (SQL, NoSQL, command, template, LDAP)
  • XSS / CSP bypasses / unsafe HTML construction
  • Auth bypass / privilege escalation / missing ownership checks
  • Secrets in code or logs (tokens, passwords, keys)
  • Insecure deserialization / unsafe eval
  • Missing rate limiting / brute-force exposure
  • CORS misconfiguration / unsafe headers
  • Data exposure (PII leak, over-fetching, missing field-level auth)

Severity Calibration

Level Meaning Examples
P0 Direct exploit, data breach, auth bypass SQL injection in public endpoint
P1 Elevated privilege or significant data leak Missing ownership check on delete
P2 Defense-in-depth gap, narrow exploit window No rate limit on login
P3 Logging of sensitive data, minor header issue Password logged in error message

Workflow

  1. Read the intent summary and diff.
  2. For each endpoint, handler, or input boundary touched:
    • Identify all user-supplied input (query params, body, headers, path segments).
    • Check if input reaches a query builder, shell, template, or eval.
    • Check auth guards: is ownership verified? Is the check on the right layer?
    • Check output construction: is user input reflected in HTML/JSON without escaping?
    • Check for secrets in strings, config, or logs.
  3. Flag any exploitable path or defense gap.

JSON Output Contract

Return exactly one JSON object:

{
  "reviewer": "security",
  "findings": [
    {
      "title": "One-line description",
      "severity": "P0|P1|P2|P3",
      "file": "relative/path",
      "line": 42,
      "confidence": 0|25|50|75|100,
      "autofix_class": "safe_auto|gated_auto|manual|advisory",
      "owner": "review-fixer|downstream-resolver|human",
      "requires_verification": true|false,
      "pre_existing": true|false,
      "suggested_fix": "If known, brief fix description"
    }
  ],
  "residual_risks": ["Architecture-level risk 1"],
  "testing_gaps": ["Missing security test for auth bypass"]
}

Read the full file on GitHub · 83 lines

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. 10d ago First seen · 83 lines · 67 tokens per session scan A 59367ef81dd0

Subscribe to this mod's changes

C31-review-security is a skill published in the GitHub repository ChianW/C31 (1 stars, last pushed 15d ago), licensed MIT. It adds 67 tokens to every session and 752 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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