cross-component

cross-component is a skill for Claude Code from allsmog/vuln-scout. It costs 62 tokens per session (1,565 once invoked), scanned A, original, MIT.

A guide to examining how separate application parts communicate, such as a frontend, backend, and internal services. It focuses on security problems that appear between components rather than inside just one of them.

In plain words
What is it for?
Use it to review service topologies, frontend-to-backend requests, internal service access, shared databases, and deployment configurations.
Why use it?
A component may look safe alone while its connections allow internal access, authentication bypasses, or data leaks. This guide helps map those interactions and trust assumptions.

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 review service topologies, frontend-to-backend requests, internal service access, shared databases, and deployment configurations.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/allsmog/vuln-scout/cross-component
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 cross-component
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 cross-component

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/allsmog/vuln-scout/cross-component"><img src="https://agentmods.dev/badge/skills/allsmog/vuln-scout/cross-component.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 62 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,565 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 $0.00062 $0.01565
Opus 5 $0.00031 $0.00783
Sonnet 5 $0.00012 $0.00313
Haiku 4.5 $0.00006 $0.00156

Measured 9d ago against content hash 876c3b816935, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

cross-component 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/cross-component/SKILL.md · 228 lines

How it starts

The opening of the file, as written. The whole thing — 228 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Cross-Component Security Analysis

Analyze how components interact and identify vulnerabilities that span service boundaries.

Why Cross-Component Analysis Matters

Single-component analysis misses:

  • SSRF in frontend reaching internal backend
  • Auth bypass when backend trusts frontend headers
  • Data leakage through shared databases
  • Privilege escalation via service-to-service calls

Step 1: Map the Architecture

Find Orchestration Configs

# Docker Compose
find . -name "docker-compose*.yml" -o -name "docker-compose*.yaml"

# Supervisord
find . -name "supervisord.conf" -o -name "supervisor*.conf"

# Kubernetes
find . -name "*.k8s.yaml" -o -name "deployment*.yaml" -o -name "service*.yaml"

# PM2
find . -name "ecosystem.config.js" -o -name "pm2*.json"

Extract Service Topology

# From docker-compose: services, ports, networks
grep -E "^\s+\w+:|ports:|expose:|depends_on:|networks:" docker-compose.yml

# From supervisord: programs and commands
grep -E "^\[program:|command=" supervisord.conf

# Internal-only services (not exposed externally)
grep -E "127\.0\.0\.1:|localhost:" docker-compose.yml supervisord.conf

Generate Service Map

## Service Topology

| Service | Port | Exposed | Language | Entry Points |
|---------|------|---------|----------|--------------|
| frontend | 1337 | ✅ External | Next.js | / |
| backend | 3000 | ❌ Internal | Flask | /api/* |
| redis | 6379 | ❌ Internal | - | - |

## Network Diagram

Internet → [1337] Next.js → [3000] Flask → [6379] Redis ↓ (Host header SSRF possible)

Step 2: Identify Trust Boundaries

Frontend → Backend Trust

# Does backend trust frontend headers?
grep -rn "X-User-ID\|X-Auth\|X-Forwarded\|X-Real-IP" --include="*.py" --include="*.go"

# Does backend skip auth for internal requests?
grep -rn "localhost\|127\.0\.0\.1\|internal" --include="*.py" --include="*.go" | grep -i "auth\|skip\|bypass"

Service-to-Service Auth

Read the full file on GitHub · 228 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. 9d ago First seen · 228 lines · 62 tokens per session scan A 876c3b816935

Subscribe to this mod's changes

cross-component is a skill published in the GitHub repository allsmog/vuln-scout (24 stars, last pushed 2mo ago), licensed MIT. It adds 62 tokens to every session and 1,565 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.

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