Ensure the HTML input name matches the PHP variable ( $_GET['num'] ).
for seamless "Add to Cart" functionality without page reloads.
// Expected format: "123:2" $num = $_GET['num'] ?? ''; if (!preg_match('/^(\d+):(\d+)$/', $num, $matches)) die('Invalid format. Use ID:QTY');
For developers, the lesson is clear: convenience kills security. If you are maintaining legacy code that uses direct GET requests or unsanitized $num variables, it is not a matter of if you will be hacked, but when . The path forward involves rigorous input validation, server-side price authority, prepared statements, CSRF tokens, and, ideally, a migration to a modern, secure framework where the pitfalls of add-cart.php are automatically mitigated by the system's architectural design.
: It is frequently used as the action attribute in an HTML form or as a direct link (e.g., Add to Cart ). add-cart.php num
Before adding to the session, verify if the requested num is available in stock.
In the world of e-commerce, the functionality to add products to a shopping cart is fundamental. However, a basic "add to cart" button isn't enough for a modern user experience. Customers often need to select quantities—for example, buying 3 of a particular item rather than just 1. This is where add-cart.php num functionality becomes crucial, allowing developers to pass both a product identifier and a specific number (quantity) to the backend.
Prevents session fixation when adding items to cart.
Are you trying to or secure a vulnerability in an existing script? Are you building a custom shopping cart from scratch? Share public link Ensure the HTML input name matches the PHP
Ensure that the incoming data matches the expected data type. If num must be a product ID, cast it explicitly to an integer and verify that it is greater than zero.
: Ensure that if a user asks for num=10 , the database actually has 10 items in stock 2.2.1 . 6. Advanced: Updating Cart Quantity (AJAX)
When a user clicks "Add to Cart," the system typically sends data to add-cart.php via a POST or GET request. The
If the script does not validate whether a product is active, hidden, or restricted, attackers can manipulate the num parameter to add unauthorized items to their cart. This includes unreleased products or items priced at zero currency units. ''; if (
Since you are modifying state (the cart), every request must include a unique token.
Furthermore, always use (via PDO or MySQLi) when querying the database for product information. Never concatenate the num or id variables directly into a SQL string.
// In the form: <input type="hidden" name="csrf_token" value="<?php echo $_SESSION['csrf_token']; ?>"> // In add-cart.php: if (!hash_equals($_SESSION['csrf_token'], $_POST['csrf_token'])) die('CSRF validation failed');
If an attacker injects 101 UNION SELECT password FROM admins , the database executes arbitrary commands. This compromises your entire backend data repository. 3. Floating-Point and Overflow Exploitation