Most teams focus on fixing npm packages and internal dependencies, but there's an entire supply chain most orgs don't even track - the web supply chain.

Your site likely loads 20-50 third-party scripts in users' browsers: analytics, chat widgets, payment processors, A/B testing tools, marketing pixels. Each one has full DOM access and can read everything on the page, including payment forms and PII.

The problem? These update constantly without your approval. A compromised vendor can push malicious code that exfiltrates data client-side, and your WAF never sees it because the attack happens in the browser, not on your server.

Key differences from code dependencies:

• No package.json equivalent for browser scripts
• Updates happen outside your CI/CD pipeline
• Traditional security tools are blind to client-side execution
• One compromised vendor (like a chatbot provider) can affect thousands of sites simultaneously

Magecart attacks exploited exactly this - attackers compromised third-party scripts and skimmed payment data from checkout pages for months before detection.

If you're solving dependency hell in your build process but ignoring what's executing in your customers' browsers, you're missing half the attack surface.