cpg-analysis

cpg-analysis is a skill for Claude Code from allsmog/vuln-scout. It costs 66 tokens per session (941 once invoked), scanned A, original, MIT.

A guide to analyzing code as a connected model of its structure, execution paths, and data dependencies. It explains Code Property Graphs and Joern, a tool for querying them.

In plain words
What is it for?
Use it to trace data flow across functions and investigate vulnerability findings in JavaScript, TypeScript, Python, Java, C, C++, Go, or PHP code.
Why use it?
Simple pattern searches may show a suspicious function but cannot reliably prove how data moves through several functions. This approach helps verify whether input reaches a sensitive operation.

Skill for Claude Code

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

Part of the vuln-scout plugin — 32 skills, 15 commands, 9 agents shipped together

Good fit Use it to trace data flow across functions and investigate vulnerability findings in JavaScript, TypeScript, Python, Java, C, C++, Go, or PHP code.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/allsmog/vuln-scout/cpg-analysis
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 allsmog/vuln-scout --skill cpg-analysis
Clone the repo
git clone --depth 1 https://github.com/allsmog/vuln-scout

Made for: Claude Code.

Or install vuln-scout, the plugin that ships this one along with the rest of its 32 skills, 15 commands, 9 agents.

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 cpg-analysis

README.md
[![agentmods](https://agentmods.dev/badge/skills/allsmog/vuln-scout/cpg-analysis/github.svg)](https://agentmods.dev/skills/allsmog/vuln-scout/cpg-analysis)
Your own site
<a href="https://agentmods.dev/skills/allsmog/vuln-scout/cpg-analysis"><img src="https://agentmods.dev/badge/skills/allsmog/vuln-scout/cpg-analysis/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 cpg-analysis

Your own site · 80×15
<a href="https://agentmods.dev/skills/allsmog/vuln-scout/cpg-analysis"><img src="https://agentmods.dev/badge/skills/allsmog/vuln-scout/cpg-analysis.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 66 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 941 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. 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 $0.00066 $0.00941
Opus 5 $0.00033 $0.00470
Sonnet 5 $0.00013 $0.00188
Haiku 4.5 $0.00007 $0.00094

Measured 9d ago against content hash dbf27dcfdc71, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

cpg-analysis scanned grade A with 0 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 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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

vuln-scout/skills/cpg-analysis/SKILL.md · 116 lines

How it starts

The opening of the file, as written. The whole thing — 116 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Code Property Graph (CPG) Analysis

What is a Code Property Graph?

A Code Property Graph (CPG) is a unified data structure that combines three representations of code:

  1. Abstract Syntax Tree (AST) - Structural representation
  2. Control Flow Graph (CFG) - Execution paths
  3. Program Dependence Graph (PDG) - Data and control dependencies

This combination enables powerful semantic queries that pattern-matching tools cannot achieve.

When to Use CPG vs Pattern Matching

Approach Use When Example
Pattern Matching (Semgrep) Known vulnerability patterns, syntax-level issues Finding dynamic code execution calls
CPG Analysis (Joern) Data flow tracking, cross-function analysis Proving request input reaches database query through 5 functions

Rule of thumb: Use CPG when you need to prove data flows between points, especially across function boundaries.

Joern Overview

Joern is the primary tool for CPG analysis. It:

  • Parses source code into CPG representation
  • Provides CPGQL (Scala-based) query language
  • Supports JavaScript, TypeScript, Python, Java, C/C++, Go, PHP

Basic Joern Workflow

# 1. Parse codebase into CPG
joern-parse /path/to/code --output cpg.bin

# 2. Start Joern REPL or run scripts
joern --script analysis.sc --params cpgFile=cpg.bin

# 3. Or use Joern REPL interactively
joern
> importCpg("cpg.bin")
> cpg.method.name(".*login.*").l

CPGQL Query Language

CPGQL uses Scala syntax with CPG-specific operations.

Core Concepts

Nodes: Represent code elements

  • cpg.method - All methods/functions
  • cpg.call - All function calls
  • cpg.parameter - Function parameters
  • cpg.literal - Literal values
  • cpg.identifier - Variable references

Traversals: Navigate the graph

  • .name("pattern") - Filter by name (regex)
  • .code("pattern") - Filter by code content
  • .argument - Get call arguments
  • .caller - Get calling methods
  • .callee - Get called methods

Read the full file on GitHub · 116 lines

Files

What ships with it

4 files 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. 9d ago First seen · 116 lines · 66 tokens per session scan A dbf27dcfdc71

Subscribe to this mod's changes

cpg-analysis is a skill published in the GitHub repository allsmog/vuln-scout (24 stars, last pushed 2mo ago), licensed MIT. It adds 66 tokens to every session and 941 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other skills, from other repositories

sast-config

Reviews and tunes SAST tool configurations against OWASP ASVS 4.0.3 and CWE Top 25. Auto-invoked when reviewing Semgrep rules, CodeQL queries, SAST CI integration, or false positive triage workflows. Produces a SAST maturity assessment covering rule authoring, severity tuning, custom rule development, and CI…

UnitOneAI/SecuritySkills · 78 tokens

sast-semgrep

Static application security testing (SAST) using Semgrep for vulnerability detection, security code review, and secure coding guidance with OWASP and CWE framework mapping. Use when: (1) Scanning code for security vulnerabilities across multiple languages, (2) Performing security code reviews with pattern-based…

AgentSecOps/SecOpsAgentKit · 116 tokens

sast-semgrep

Static application security testing (SAST) using Semgrep for vulnerability detection, security code review, and secure coding guidance with OWASP and CWE framework mapping. Use when: (1) Scanning code for security vulnerabilities across multiple languages, (2) Performing security code reviews with pattern-based…

rohunj/claude-build-workflow · 116 tokens

release-it

Build production-ready systems with stability patterns: circuit breakers, bulkheads, timeouts, and retry logic. Use when the user mentions "production outage", "circuit breaker", "deployment pipeline", "chaos engineering", "retry storm", "health checks", "my service keeps crashing", "prevent cascading failures", or…

wondelai/skills · 131 tokens

tidewave-integration

Tidewave MCP runtime tools — debugging, smoke testing, live state inspection, SQL queries, hex docs. Use when evaluating code in a running Phoenix app.

oliver-kriska/claude-elixir-phoenix · 38 tokens

debug

Interactive debugging workflow with hypothesis-driven probe loop. Use when: unknown bugs, script errors, silent failures, troubleshooting. Not for: known bugs (use bug-fix), GitHub issue analysis (use issue-analyze), code understanding (use code-explore). Output: debug report with probe journal + root cause + fix.

sd0xdev/sd0x-harness · 67 tokens