Fix API Rate Limit Exhaustion in Actix Web
API Rate Limit Exhaustion is a critical vulnerability that allows attackers to perform Denial of Service (DoS) attacks or brute-force endpoints by flooding the server with requests. In the Actix Web ecosystem, failing to implement middleware-level throttling means every request hits your business logic and database, leading to rapid resource depletion and potential service outages.
The Vulnerable Pattern
use actix_web::{get, App, HttpResponse, HttpServer, Responder};#[get(“/api/resource”)] async fn public_api() -> impl Responder { // Vulnerable: No rate limiting logic. // An attacker can spam this endpoint to exhaust worker threads or DB connections. HttpResponse::Ok().body(“Data delivered”) }
#[actix_web::main] async fn main() -> std::io::Result<()> { HttpServer::new(|| { App::new().service(public_api) }) .bind((“127.0.0.1”, 8080))? .run() .await }
The Secure Implementation
The secure implementation leverages `actix-extensible-rate-limit` to intercept requests before they reach the handler. We utilize an `InMemoryBackend` to store request counts and a `SimpleInputFunctionBuilder` to identify clients by their real IP address. The policy restricts users to 10 requests per minute. Once the threshold is crossed, the middleware automatically returns a '429 Too Many Requests' response, shielding the application logic from overhead. The `.add_headers()` call ensures 'X-RateLimit' headers are sent, notifying well-behaved clients of their remaining quota.
use actix_web::{get, App, HttpResponse, HttpServer, Responder}; use actix_extensible_rate_limit::{ backend::memory::InMemoryBackend, backend::SimpleInputFunctionBuilder, RateLimiter, }; use std::time::Duration;#[get(“/api/resource”)] async fn public_api() -> impl Responder { HttpResponse::Ok().body(“Data delivered”) }
#[actix_web::main] async fn main() -> std::io::Result<()> { // 1. Initialize an in-memory storage backend for tracking hits let backend = InMemoryBackend::builder().build();
HttpServer::new(move || { // 2. Define limit: 10 requests per 60 seconds per IP let input = SimpleInputFunctionBuilder::new(Duration::from_secs(60), 10) .real_ip_key() .build(); // 3. Construct middleware let middleware = RateLimiter::builder(backend.clone(), input) .add_headers() .build(); App::new() .wrap(middleware) .service(public_api) }) .bind(("127.0.0.1", 8080))? .run() .await
}
Your Actix Web API
might be exposed to API Rate Limit Exhaustion
74% of Actix Web apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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