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Fix Unrestricted Resource Consumption in Go Fiber

Unrestricted resource consumption in Go Fiber is a classic DoS vector where an attacker exhausts memory, CPU, or file descriptors due to lack of constraints. Fiber's default configuration prioritizes performance over security, meaning it will happily attempt to buffer massive payloads or maintain thousands of slow connections until the process OOMs (Out of Memory) or stops accepting new traffic.

The Vulnerable Pattern

package main

import “github.com/gofiber/fiber/v2”

func main() { // VULNERABLE: Default config has a 4GB BodyLimit and no timeouts app := fiber.New()

app.Post("/upload", func(c *fiber.Ctx) error {
    // An attacker can stream a multi-gigabyte file here
    // causing the server to crash due to memory exhaustion.
    return c.SendString("Upload received")
})

app.Listen(":3000")

}

The Secure Implementation

To harden Fiber against resource exhaustion, you must apply a multi-layered defense. First, 'BodyLimit' is set in the fiber.Config to prevent large payloads from saturating RAM. Second, 'ReadTimeout' and 'WriteTimeout' are essential to kill 'Slowloris' style attacks where a client holds a connection open indefinitely. Finally, the 'limiter' middleware is implemented to throttle the request rate per IP, ensuring that a single malicious actor cannot monopolize the thread pool or backend resources via request flooding.

package main

import ( “time” “github.com/gofiber/fiber/v2” “github.com/gofiber/fiber/v2/middleware/limiter” )

func main() { // SECURE: Strict BodyLimit and aggressive timeouts app := fiber.New(fiber.Config{ BodyLimit: 2 * 1024 * 1024, // Limit to 2MB ReadTimeout: 10 * time.Second, WriteTimeout: 10 * time.Second, IdleTimeout: 30 * time.Second, })

// SECURE: Rate limiting to prevent CPU/Network exhaustion
app.Use(limiter.New(limiter.Config{
    Max:        20,
    Expiration: 1 * time.Minute,
    KeyGenerator: func(c *fiber.Ctx) string {
        return c.IP()
    },
}))

app.Post("/upload", func(c *fiber.Ctx) error {
    return c.SendString("Upload restricted and secured")
})

app.Listen(":3000")

}

System Alert • ID: 1831
Target: Go Fiber API
Potential Vulnerability

Your Go Fiber API might be exposed to Unrestricted Resource Consumption

74% of Go Fiber apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.

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