Fix Lack of Resources & Rate Limiting in Blitz.js
Blitz.js leverages RPC-style mutations and queries. By default, these endpoints lack throttling, making them trivial targets for DoS via resource exhaustion or credential stuffing. To harden the application, we must implement rate limiting at the resolver level or via global middleware to ensure expensive operations like password resets or complex DB lookups don't crash the instance.
The Vulnerable Pattern
import { resolver } from "@blitzjs/rpc" import db from "db"
export default resolver.pipe( async ({ email }) => { // VULNERABILITY: No rate limiting on a high-resource or sensitive operation const user = await db.user.findFirst({ where: { email } }) if (user) { // Trigger expensive email sending service await sendResetEmail(user.email) } return true } )
The Secure Implementation
The secure implementation utilizes the 'rate-limiter-flexible' library within the Blitz resolver pipe. Before any business logic is executed, we identify the client by IP address and check the consumption of 'points'. If the client exceeds 5 requests within 15 minutes, the pipe terminates immediately with an error, preventing downstream resource exhaustion (DB connections, SMTP server load). For horizontally scaled apps, use a Redis back-end to synchronize rate limits across multiple nodes.
import { resolver } from "@blitzjs/rpc" import { RateLimiterMemory } from "rate-limiter-flexible"// In production, use RateLimiterRedis for distributed environments const rateLimiter = new RateLimiterMemory({ points: 5, duration: 900, // 15 minutes })
export default resolver.pipe( async (input, ctx) => { const ip = ctx.req.socket.remoteAddress || “unknown” try { await rateLimiter.consume(ip) } catch (rejRes) { throw new Error(“Too many requests. Try again in 15 minutes.”) } return input }, async ({ email }) => { const user = await db.user.findFirst({ where: { email } }) if (user) { await sendResetEmail(user.email) } return true } )
Your Blitz.js API
might be exposed to Lack of Resources & Rate Limiting
74% of Blitz.js apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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