diff --git a/vendor/magento/module-persistent/Model/Plugin/AllowPersistentCustomerGuestCart.php b/vendor/magento/module-persistent/Model/Plugin/AllowPersistentCustomerGuestCart.php
new file mode 100644
index 0000000000000..5ba173320b2ad
--- /dev/null
+++ b/vendor/magento/module-persistent/Model/Plugin/AllowPersistentCustomerGuestCart.php
@@ -0,0 +1,58 @@
+<?php
+/**
+ * Copyright 2026 Adobe
+ * All Rights Reserved.
+ */
+declare(strict_types=1);
+
+namespace Magento\Persistent\Model\Plugin;
+
+use Magento\Customer\Model\Session as CustomerSession;
+use Magento\Persistent\Helper\Data as PersistentHelper;
+use Magento\Persistent\Helper\Session as PersistentSession;
+use Magento\Quote\Model\GuestCart\GetGuestCart;
+
+/**
+ * @SuppressWarnings(PHPMD.CookieAndSessionMisuse)
+ */
+class AllowPersistentCustomerGuestCart
+{
+    /**
+     * @param CustomerSession $customerSession
+     * @param PersistentSession $persistentSession
+     * @param PersistentHelper $persistentHelper
+     */
+    public function __construct(
+        private readonly CustomerSession $customerSession,
+        private readonly PersistentSession $persistentSession,
+        private readonly PersistentHelper $persistentHelper
+    ) {
+    }
+
+    /**
+     * Allow the guest checkout endpoints to read a cart that still belongs to a persisted customer.
+     *
+     * @param GetGuestCart $subject
+     * @param callable $proceed
+     * @param int $customerId
+     * @param string $maskedCartId
+     * @return void
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function aroundCheckIsGuestCart(
+        GetGuestCart $subject,
+        callable $proceed,
+        int $customerId,
+        string $maskedCartId
+    ): void {
+        $isOwnedByPersistedCustomer = $customerId !== 0
+            && $this->persistentHelper->isShoppingCartPersist()
+            && !$this->customerSession->isLoggedIn()
+            && $this->persistentSession->isPersistent()
+            && (int) $this->persistentSession->getSession()->getCustomerId() === $customerId;
+
+        if (!$isOwnedByPersistedCustomer) {
+            $proceed($customerId, $maskedCartId);
+        }
+    }
+}
diff --git a/vendor/magento/module-persistent/etc/di.xml b/vendor/magento/module-persistent/etc/di.xml
index bec28c0bbbcfd..e233ac9a4adb5 100644
--- a/vendor/magento/module-persistent/etc/di.xml
+++ b/vendor/magento/module-persistent/etc/di.xml
@@ -25,4 +25,7 @@
     <type name="Magento\Quote\Model\QuoteManagement">
         <plugin name="persistent_convert_customer_cart_to_guest_cart" type="Magento\Persistent\Model\Plugin\ConvertCustomerCartToGuest" />
     </type>
+    <type name="Magento\Quote\Model\GuestCart\GetGuestCart">
+        <plugin name="persistent_allow_guest_cart_access" type="Magento\Persistent\Model\Plugin\AllowPersistentCustomerGuestCart" />
+    </type>
 </config>