Web Application Security Best Practices: Production Hardening Guide

1. The Modern Web Threat Model

Web applications handle increasingly sensitive consumer data, proprietary workflows, and financial transactions. Relying solely on default framework configurations leaves fatal vulnerabilities open to automated scanning bots.

Authentication & Token Hardening: Never store access tokens in `localStorage` or `sessionStorage` where they are trivially accessible via Cross-Site Scripting (XSS). Store session identifiers in `__Host-` prefixed `httpOnly`, `Secure`, `SameSite=Strict` cookies.

SQL & NoSQL Injection Defense: Always enforce parameterized queries or strictly typed ORMs (Prisma, Drizzle, Mongoose). Never concatenate raw user input strings into database execution clauses.

// Secure Cookie Header Configuration in Next.js Server Actions
import { cookies } from "next/headers";

export async function setSecureSession(token: string) {
  const cookieStore = await cookies();
  cookieStore.set("__Host-session", token, {
    httpOnly: true,
    secure: process.env.NODE_ENV === "production",
    sameSite: "strict",
    path: "/",
    maxAge: 60 * 60 * 24 * 7, // 7 days
  });
}

2. Content Security Policy (CSP) & Defense-in-Depth

A strict Content Security Policy is your final line of defense against XSS and malicious third-party script injection. Enforce cryptographic nonces for inline scripts and restrict `connect-src` only to authorized API domains.

Automated Dependency Scanning: Integrate Dependabot, Snyk, and GitHub CodeQL into your continuous integration pipeline. Block production merges whenever high or critical CVE vulnerabilities are detected in npm packages.