Add-cart.php Num ((free)) Guide

At first glance, a URL like https://www.yourstore.com/add-cart.php?id=105&num=1 seems harmless. It tells the server: "Add product ID 105 to the cart, quantity 1 (num=1)."

// Vulnerable Code $quantity = $_GET['num']; // If user sends ?num=-5, this is accepted.

The component refers to a parameter (often passed via $_GET or $_POST ) that dictates the number of items to add. URL Example: add-cart.php?id=101&num=3 Action: Adds 3 units of Product ID 101 to the cart. 1. Frontend: Creating the Dynamic Input

// Vulnerable code $id = $_GET['num']; $result = mysqli_query($conn, "SELECT * FROM products WHERE id = $id");

They send a phishing email: Click here to add to cart: https://store.com/add-cart.php?id=777&num=1&PHPSESSID=attacker_controlled add-cart.php num

: The client sends a GET or POST request containing parameters like num (Product ID) and often qty (Quantity).

// 3. Optional: check product existence in the database // (using a prepared statement to prevent SQL injection) $stmt = $pdo->prepare("SELECT name, price, stock FROM products WHERE id = ?"); $stmt->execute([$productId]); $product = $stmt->fetch(PDO::FETCH_ASSOC); if (!$product) die('Product does not exist.');

If you don't handle this correctly, your cart will simply overwrite the item instead of incrementing it, leading to a frustrating user experience. In this guide, we will break down how to create a robust add-cart.php

This tells the server: "Add 3 units of product ID 101 to the cart." 2. Setting Up the Cart Session At first glance, a URL like https://www

Use code with caution. 3. Best Practices for add-cart.php num

Do not rely on your frontend JavaScript to enforce maximum purchasing limits. If a product has only 2 units left in stock, your PHP script must double-check the database inventory before honoring the user's requested num value. 4. UI/UX Best Practices for Managing Item Quantities

header('Location: products.php?error=stock_limit_exceeded'); exit;

To prevent attackers from abusing add-cart.php remotely, implement CSRF protection. Generate a unique token for each session and embed it in the form. URL Example: add-cart

<?php session_start();

Using explicit file parameters like add-cart.php?num= exposes the internal structure of an application, making it a frequent target for automated vulnerability scanners and malicious actors. 1. Insecure Direct Object References (IDOR)

Use code with caution. 3. Creating the add-cart.php Logic

$stock_query = "SELECT quantity FROM inventory WHERE product_id = " . $_GET['id'] . " AND num = " . $_GET['num']; // ^^^^^^^^^^^^^ // Injection point