Fix Business Logic Errors in Qwik
Business logic errors in Qwik typically manifest within 'server$' functions or 'routeLoader$' blocks where developers mistakenly trust client-provided state. Because Qwik serializes and 'resumes' application state, it's easy to forget that the server-side RPCs are public endpoints. Attackers can intercept these requests and modify parameters like prices, user IDs, or roles if you aren't re-validating the state against your source of truth on the backend.
The Vulnerable Pattern
import { component$ } from '@builder.io/qwik'; import { server$ } from '@builder.io/qwik-city';// VULNERABLE: The server trusts the price sent from the client-side state. export const checkoutAction = server$(async (totalPrice: number) => { const user = await getSession(); if (user) { await db.orders.create({ data: { amount: totalPrice, userId: user.id } }); return { success: true }; } });
export default component$(() => { const cartTotal = 500.00; return <button onClick$={() => checkoutAction(0.01)}>Buy for $0.01; });
The Secure Implementation
The vulnerability lies in 'Parameter Tampering' within the Qwik server RPC. In the vulnerable snippet, an attacker can modify the 'totalPrice' argument in the POST request to the 'server$' endpoint. The fix involves treating every 'server$' function as a zero-trust API. Instead of accepting the final price, the server accepts only the identifiers (productIds), re-fetches the authoritative data from the database, and performs the calculation in a trusted environment. Always validate session ownership and recalculate business-critical values on the server.
import { component$ } from '@builder.io/qwik'; import { server$ } from '@builder.io/qwik-city';// SECURE: Server recalculates the truth based on Product IDs, ignoring client-side math. export const checkoutAction = server$(async (productIds: string[]) => { const user = await getSession(); if (!user) throw new Error(‘Unauthorized’);
// Fetch current prices directly from the DB const products = await db.products.findMany({ where: { id: { in: productIds } } }); const actualTotal = products.reduce((sum, p) => sum + p.price, 0);
await db.orders.create({ data: { amount: actualTotal, userId: user.id } }); return { success: true }; });
export default component$(() => { const items = [‘p1’, ‘p2’]; return <button onClick$={() => checkoutAction(items)}>Checkout Securely; });
Your Qwik API
might be exposed to Business Logic Errors
74% of Qwik apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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