GHSA-vff3-pqq8-4cpq

An Insecure Direct Object Reference (IDOR) vulnerability exists in Craft Commerce’s cart functionality that allows users to hijack any shopping cart by knowing or guessing its 32-character number. This vulnerability enables the takeover of shopping sessions and potential exposure of PII.

## Vulnerability Details

### Root Cause

The `CartController` accepts a user-supplied `number` parameter to load and modify shopping carts. No ownership validation is performed - the code only checks if the order exists and is incomplete, not whether the requester has authorization to access it.

```php // CartController.php:374-389 - actionLoadCart() public function actionLoadCart(): ?Response { $number = $this->request->getParam('number');

if ($number === null) { return $this->asFailure(Craft::t('commerce', 'A cart number must be specified.')); }

// No ownership check - returns any cart to any requester $cart = Order::find()->number($number)->isCompleted(false)->one();

// Cart is loaded into attacker's session without authorization ... } ```

```php // CartController.php:606-616 - _getCart() $orderNumber = $this->request->getBodyParam('number'); if ($orderNumber) { // Same issue - no ownership validation $cart = Order::find()->number($orderNumber)->isCompleted(false)->one(); // Returns cart to any requester who knows the number } ``` ---

## Attack Scenario

### Prerequisites - Target Craft Commerce installation with active shopping carts - Knowledge of a victim’s cart number (32-character hex string)

### Cart Number Acquisition Vectors

1. **Referrer Header Leakage**: Cart URLs shared externally expose the number 2. **Browser History**: Accessible on shared/compromised devices 3. **Proxy/WAF Logs**: Cart numbers logged in URL parameters 4. **Social Engineering**: Support tickets, screenshots containing cart URLs 5. **Brute Force**: While impractical for random targeting, feasible for targeted attacks against recently-created carts

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