Keeping JavaScript Dependencies Secure: An Essential Guide

In modern web applications, security extends far beyond the code we write. With JavaScript projects relying on hundreds of third-party packages, keeping these dependencies updated and vulnerability-free has become a crucial aspect of secure software development.

Currently, on my squad, we use vulnerability information to guide our update prioritization strategy. Our focus remains primarily on addressing high and critical issues in production dependencies, as these pose the most immediate risks to our systems. By sharing our approach and experiences through this guide, I aim to help you make informed decisions about your own project's security and establish effective update workflows. Understanding when and what to update isn't just about following best practices—it's about developing a practical, risk-based approach that protects your applications while maintaining development efficiency.

---

Why Care About Dependency Updates?

Consider building a house: you don't just worry about the quality of your materials, but also about the integrity of every component you use, from locks to electrical installations. Similarly, each dependency in your project is like a component of that house, and a single vulnerability can compromise the entire structure.

In 2021, a Snyk study revealed that 84% of web application vulnerabilities came from third-party dependencies. This means that even with impeccable code, your application might be exposed to significant risks through the libraries it uses.

---

How to Identify Vulnerabilities in Your Project

NPM provides a powerful integrated security analysis tool: npm audit. Let's explore how to use it effectively:

Running a Basic Audit

To perform a basic security check, run in your terminal:

npm audit

This command will analyze your package-lock.json file and report any vulnerabilities found. A typical output looks like this:

# npm audit report

axios  <0.21.1
Severity: high
Prototype Pollution in axios - https://github.com/advisories/GHSA-7rjr-3q55-vv33
fix available via `npm audit fix`
node_modules/axios
  react-scripts  *
  depends on axios@0.19.2
  node_modules/react-scripts

1 high severity vulnerability

Understanding the Vulnerability Report

The report classifies vulnerabilities into different levels:

• low: Minimal impact, usually non-critical
• moderate: Potential to cause problems under certain circumstances
• high: Serious vulnerabilities that should be addressed quickly
• critical: Severe flaws requiring immediate attention

Fixing Found Vulnerabilities

To automatically fix found vulnerabilities, you can use:

npm audit fix

For more complex cases that might cause breaking changes:

npm audit fix --force

⚠️ Warning: Using --force should be done with caution as it may break your application's compatibility.

---

Deep Dive into Dependency Investigation

Sometimes a vulnerability alert requires more than just a quick fix. A thorough dependency investigation can reveal opportunities for both security improvements and codebase modernization. This investigation process involves several key aspects that might not be immediately obvious from security reports alone.

When investigating a dependency, consider its entire ecosystem: recent releases, community activity, maintenance status, and most importantly, compatibility with your project. This comprehensive review helps you make an informed decision between a simple patch update and a major version migration. For instance, if you're dealing with a vulnerability in an older version of Express.js, you might discover that upgrading to the latest major version not only resolves security issues but also brings performance improvements and new features that could benefit your application.

Testing Strategy for Safe Updates

Before implementing any dependency updates in production, it's crucial to validate them through a comprehensive testing strategy. Here's a methodical approach to ensure safe updates:

1. Unit Tests: Verify that individual components still function correctly with the updated dependencies. Pay special attention to components that directly interact with the updated packages.

2. Integration Tests: Ensure that different parts of your application still work together seamlessly. This is particularly important when updating packages that handle data flow or state management.

3. End-to-End (E2E) Tests: Run complete user journey tests to catch any issues that might only appear in fully integrated scenarios.

4. Regression Testing: This crucial step helps identify if the updates have inadvertently affected existing functionality. Consider implementing:

   • Automated regression test suites
   • Manual testing of critical user paths
   • Performance regression testing, especially for core functionality

Real-World Example

Consider a recent case where updating a React-based UI library required investigation:

// Old version with vulnerability
"react-ui-library": "^2.5.0"  // Known XSS vulnerability

// After investigation, we found two potential paths:
// Option 1: Patch update
"react-ui-library": "^2.5.8"  // Patches XSS but keeps same API

// Option 2: Major version upgrade
"react-ui-library": "^3.0.0"  // Completely new API, better security model

In this case, a proper investigation revealed that while the patch update (Option 1) would fix the immediate security concern, the major version upgrade (Option 2) offered a more robust security model and better long-term maintainability. However, this decision could only be made after thorough testing and evaluation of the migration effort required.

---

Best Practices for Continuous Maintenance

Maintain a Change Log

Document all significant dependency updates, including:

• Update date
• Updated packages
• Reason for update
• Impact on existing functionalities

Configure Automatic Alerts

Use tools like GitHub Dependabot or Snyk to receive automatic alerts about new vulnerabilities.

---

Additional Recommended Tools

Beyond npm audit, consider using:

• Jest Security Check: For projects using Jest as the testing framework
• OWASP Dependency-Check: A tool that can be integrated into your CI/CD pipeline

---

Conclusion

Keeping your dependencies updated isn't just about having the latest features—it's a critical security necessity. Establish a regular update and audit process, and treat it as a fundamental part of your project's lifecycle.

Remember: in software security, prevention is always better than remediation. A small regular time investment in dependency maintenance can prevent major headaches in the future.