| Usage | Example | Meaning | |-------|---------|---------| | Quantity only | ?num=3 | Add 3 units of a predefined product | | Product ID | ?num=SKU456 | Add 1 unit of product SKU456 | | ID:Quantity | ?num=101:2 | Add 2 units of product ID 101 | | Encoded value | ?num=eyJpZCI6MjN9 | Base64‑encoded JSON |
INSERT INTO cart (user_id, product_id, quantity) VALUES (?, ?, ?) ON DUPLICATE KEY UPDATE quantity = quantity + VALUES(quantity);
If stock < requested quantity, cap quantity or show error. add-cart.php num
If the num variable represents a product ID and is concatenated directly into a database query string, an attacker can append malicious payloads. This exploit lets attackers bypass authentication mechanisms or leak the entire customer database.
$stmt = $pdo->prepare("SELECT stock FROM products WHERE id = ?"); $stmt->execute([$productId]); $product = $stmt->fetch(); | Usage | Example | Meaning | |-------|---------|---------|
This article dissects the add-cart.php script, focusing specifically on the num parameter. We will explore what it does, why it’s a red flag for security, how attackers exploit it, and how to rebuild it correctly.
A vulnerable script might look like this: The user may end up with a cart
Use addslashes() or log in structured formats (JSON) with strict key validation.
The user may end up with a cart full of items they never intended to buy, leading to a poor experience and possible confusion at checkout.
In most tutorials, such as those found on PHPpot , the logic follows this pattern: