Fix Broken User Authentication in Gatsby
Gatsby's static nature creates a dangerous illusion of security. Developers often mistake client-side routing for access control. If your 'protected' data is baked into a static HTML file and hidden by a simple useEffect hook, you've already lost. Broken authentication in Gatsby typically stems from exposing sensitive content in the static build or relying on insecure client-side storage like localStorage for session management.
The Vulnerable Pattern
// src/pages/dashboard.js
import React, { useEffect } from 'react'
import { navigate } from 'gatsby'
const Dashboard = () => {
// VULNERABILITY: Sensitive content is rendered in the static HTML build
// and only ‘hidden’ after the JS mounts. LocalStorage is also XSS-prone.
useEffect(() => {
const token = localStorage.getItem(‘auth_token’)
if (!token) {
navigate(‘/login’)
}
}, [])
return (
Admin Dashboard
Secret API Key: AIzaSyB-89234_HIDDEN_IN_PLAIN_SIGHT
)
}
export default DashboardThe Secure Implementation
To fix broken auth, you must decouple sensitive data from the static build. First, use gatsby-node.js to define 'Client-only routes' via matchPath; this prevents Gatsby from pre-rendering sensitive content into static HTML files. Second, implement a PrivateRoute wrapper that checks for a valid session (preferably via HttpOnly cookies, not localStorage) before mounting the component. Third, ensure your Auth provider verifies the JWT/session server-side on every request to your backend API. If the client-side state is spoofed, the API must still return 401 Unauthorized.
// gatsby-node.js exports.onCreatePage = async ({ page, actions }) => { const { createPage } = actions if (page.path.match(/^\/dashboard/)) { page.matchPath = '/dashboard/*' createPage(page) } }// src/components/PrivateRoute.js import React from ‘react’ import { navigate } from ‘gatsby’ import { useAuth } from ’../hooks/use-auth’
const PrivateRoute = ({ component: Component, …rest }) => { const { user, loading } = useAuth() if (loading) return null if (!user) { navigate(‘/login’) return null } return <Component {…rest} /> } export default PrivateRoute
Your Gatsby API
might be exposed to Broken User Authentication
74% of Gatsby apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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