GHSA-vff3-pqq8-4cpq Craft Commerce: Potential IDOR in Commerce carts

• Packagist craftcms/commerce: >= 5.0.0, < 5.6.0 → fixed in 5.6.0 • Packagist craftcms/commerce: >= 4.0.0, < 4.11.0 → fixed in 4.11.0

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 ---