Magento Long Term Support (LTS) is an unofficial, community-driven project provides an alternative to the Magento Community Edition e-commerce platform with a high level of backward compatibility. Prior to version 20.17.0, the shared wishlist add-to-cart endpoint authorizes access with a public `sharing_code`, but loads the acted-on wishlist item by a separate global `wishlist_item_id` and never verifies that the item belongs to the shared wishlist referenced by that code. This lets an attacker use a valid shared wishlist code for wishlist A and a wishlist item ID belonging to victim wishlist B to import victim item B into the attacker's cart through the shared wishlist flow for wishlist A. Because the victim item's stored `buyRequest` is reused during cart import, the victim's private custom-option data is copied into the attacker's quote. If the product uses a file custom option, this can be elevated to cross-user file disclosure because the imported file metadata is preserved and the download endpoint is not ownership-bound. Version 20.17.0 patches the issue.

Affected: Packagist: openmage/magento-lts

# Cross-user wishlist item import via shared wishlist code, leading to private option disclosure and file-disclosure variant

## Summary

The shared wishlist add-to-cart endpoint authorizes access with a public `sharing_code`, but loads the acted-on wishlist item by a separate global `wishlist_item_id` and never verifies that the item belongs to the shared wishlist referenced by that code.

This lets an attacker use:

- a valid shared wishlist code for wishlist A - a wishlist item ID belonging to victim wishlist B

to import victim item B into the attacker's cart through the shared wishlist flow for wishlist A.

Because the victim item's stored `buyRequest` is reused during cart import, the victim's private custom-option data is copied into the attacker's quote. If the product uses a file custom option, this can be elevated to cross-user file disclosure because the imported file metadata is preserved and the download endpoint is not ownership-bound.

## Vulnerability Type

- Broken object-level authorization / IDOR - Cross-user data disclosure - Cross-user file disclosure variant

## Root Cause

In `app/code/core/Mage/Wishlist/controllers/SharedController.php`, the shared flow does:

```php $item = Mage::getModel('wishlist/item')->load($itemId); $wishlist = Mage::getModel('wishlist/wishlist')->loadByCode($code); ... $item->addToCart($cart); ```

Relevant lines:

- `SharedController.php:86` loads the wishlist item by global ID - `SharedController.php:87` loads the wishlist by…