Fix BFLA (Broken Function Level Authorization) in Gatsby
Gatsby's serverless functions (API routes) are often the weakest link. BFLA (Broken Function Level Authorization) occurs when sensitive administrative endpoints are exposed to lower-privileged users because the developer assumes the UI's 'hidden' buttons are enough protection. In a headless or hybrid Gatsby app, if your API doesn't explicitly verify the user's role server-side, an attacker can simply replay the request with a standard user token—or no token at all—to execute privileged actions.
The Vulnerable Pattern
// src/api/admin/delete-user.js
export default async function handler(req, res) {
// VULNERABILITY: The function only checks if the request is a POST.
// It fails to verify if the requester has 'ADMIN' privileges.
if (req.method === 'POST') {
const { userId } = req.body;
await database.users.delete(userId);
return res.status(200).json({ message: 'User deleted successfully' });
}
res.status(405).send('Method Not Allowed');
}The Secure Implementation
The fix moves authorization from the 'implicit' client-side (hiding components) to the 'explicit' server-side. The secure implementation uses a middleware-style pattern to first verify the identity of the caller (Authentication) and then specifically checks if that identity possesses the 'ADMIN' role (Authorization) before touching the database. We use a 'Deny by Default' approach where if the role check fails, a 403 Forbidden status is returned immediately, preventing unauthorized access to the business logic.
// src/api/admin/delete-user.js import { verifySession, isAdmin } from '../../utils/auth-logic';export default async function handler(req, res) { try { // 1. Authenticate: Validate the JWT/Session const user = await verifySession(req);
// 2. Authorize: Explicitly check for Function Level permissions if (!isAdmin(user)) { return res.status(403).json({ error: 'Access Denied: Administrative rights required' }); } if (req.method === 'POST') { const { userId } = req.body; await database.users.delete(userId); return res.status(200).json({ message: 'User deleted securely' }); }
} catch (error) { return res.status(401).json({ error: ‘Unauthorized’ }); } }
Your Gatsby API
might be exposed to BFLA (Broken Function Level Authorization)
74% of Gatsby apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
Free Tier • No Credit Card • Instant Report
Verified by Ghost Labs Security Team
This content is continuously validated by our automated security engine and reviewed by our research team. Ghost Labs analyzes over 500+ vulnerability patterns across 40+ frameworks to provide up-to-date remediation strategies.