Fix BFLA (Broken Function Level Authorization) in Blitz.js

BFLA in Blitz.js occurs when internal RPC endpoints expose administrative logic to unprivileged users. Unlike IDOR, which targets data instances, BFLA targets functional capabilities. If you aren't enforcing Role-Based Access Control (RBAC) directly within your mutation and query pipes, any user can trigger privileged actions by hitting the auto-generated API endpoints.

The Vulnerable Pattern

import { resolver } from '@blitzjs/rpc';
import db from 'db';
export default resolver.pipe(
async ({ id }) => {
// VULNERABLE: No authorization check.
// Any authenticated user can call this RPC to delete others.
const user = await db.user.delete({ where: { id } });
return user;
}
);

The Secure Implementation

The fix utilizes the `resolver.authorize` middleware within the Blitz.js pipe architecture. By placing `resolver.authorize('ADMIN')` at the start of the pipe, the framework intercepts the request and validates the session's role against the required permission. If the user lacks the 'ADMIN' role, Blitz throws an `AuthorizationError`, preventing the execution of the sensitive database operation. Never rely on client-side UI masking; the server-side resolver is the only source of truth for authorization.

import { resolver } from '@blitzjs/rpc';
import db from 'db';
export default resolver.pipe(
resolver.authorize(‘ADMIN’), // SECURE: Enforces ‘ADMIN’ role check
async ({ id }, ctx) => {
// Logic only executes if session.role === ‘ADMIN’
const user = await db.user.delete({ where: { id } });
return user;
}
);