Dependency Scanning

Modern applications rely heavily on third-party dependencies—often 80-90% of your codebase consists of external packages. This creates a massive attack surface: a single vulnerable dependency can compromise your entire application.

Dependency scanning tools automatically detect known vulnerabilities in your dependencies and help you remediate them before attackers exploit them.

Why Dependency Scanning Matters

High-profile breaches have demonstrated the risk:

• Equifax (2017) — Unpatched Apache Struts vulnerability led to 147 million records exposed
• Log4Shell (2021) — Log4j vulnerability affected millions of applications worldwide
• event-stream (2018) — Malicious code injected into popular npm package

These incidents share a common theme: known vulnerabilities in dependencies that could have been detected and fixed.

What You'll Learn

This guide covers the essential tools and techniques for dependency security:

1. Fundamentals — How dependency scanning works, vulnerability databases, and severity scoring
2. Snyk — Industry-leading tool for finding and fixing vulnerabilities across languages
3. GitHub Dependabot — Free, built-in scanning and automated PRs for GitHub repositories
4. Native Tools — npm audit, pip-audit, bundler-audit, and other language-specific scanners

Quick Comparison

Tool	Languages	CI/CD Integration	Auto-Fix PRs	Free Tier
Snyk	10+	Excellent	Yes	200 tests/month
Dependabot	15+	GitHub native	Yes	Unlimited (GitHub)
npm audit	JavaScript	Manual	No	Free
pip-audit	Python	Manual	No	Free
trivy	Containers + IaC	Good	No	Free

Prerequisites

Before starting, you should:

• Understand package managers (npm, pip, Maven, etc.)
• Have basic CI/CD knowledge
• Have access to a project with dependencies to scan

Time Investment

• Quick start: 30 minutes (run your first scan)
• Full implementation: 2-4 hours (CI/CD integration + policies)
• Mastery: Ongoing (vulnerability triage and remediation workflows)