Fix API Rate Limit Exhaustion in Nitro
Nitro's high-performance event loop is easily choked by unauthenticated resource exhaustion. Default routes lack built-in throttling, allowing attackers to script-flood expensive endpoints, leading to DoS or massive DB billing. Mitigation requires intercepting the H3 event and enforcing a strict sliding window or token bucket strategy using a persistent storage backend like Redis.
The Vulnerable Pattern
export default defineEventHandler(async (event) => {
// VULNERABLE: Direct execution of expensive logic without rate validation.
// An attacker can trigger this 10,000 times per second to exhaust DB connections.
const query = getQuery(event);
const result = await db.complexSearch(query.q);
return { result };
});The Secure Implementation
The secure implementation utilizes Nitro's `useStorage` to maintain state across requests. It extracts the client IP (honoring proxy headers) and increments a counter within a TTL window. If the threshold is breached, it short-circuits the request with an HTTP 429. For production environments, the storage mount should be configured to use Redis in `nitro.config.ts` to ensure rate limits persist across worker threads and container restarts.
import { defineEventHandler, createError, getRequestIP } from 'h3';export default defineEventHandler(async (event) => { const storage = useStorage(‘cache’); const ip = getRequestIP(event, { xForwardedFor: true }) || ‘unknown’; const key =
rate-limit:${ip}; const limit = 50; // Max requests const window = 60 * 1000; // 1 minuteconst current = await storage.getItem(key) || { count: 0, reset: Date.now() + window };
if (Date.now() > current.reset) { current.count = 0; current.reset = Date.now() + window; }
if (current.count >= limit) { throw createError({ statusCode: 429, statusMessage: ‘Rate Limit Exceeded’, data: { retryAfter: Math.ceil((current.reset - Date.now()) / 1000) } }); }
current.count++; await storage.setItem(key, current);
const query = getQuery(event); return await db.complexSearch(query.q); });
Your Nitro API
might be exposed to API Rate Limit Exhaustion
74% of Nitro apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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