Input Validation

When to Use

• Building or reviewing API endpoints that accept user input
• Working with database queries, HTML rendering, or form handling
• Auditing an existing application for injection vulnerabilities
• Adding validation middleware to a web framework
• Handling file uploads, URL parameters, or header values

Prerequisites

• Understanding of the application's input surfaces (APIs, forms, file uploads)
• Access to the codebase's request handlers and data layer
• A validation library available (zod, joi, express-validator, etc.)

Workflow

1. Map Input Surfaces