xt:Commerce version 5.4.1, 6.2.1, and 6.2.2 suffer from an improper access control vulnerability. A logged-in customer can create and alter addresses. These addresses are referenced by incrementing IDs. On saving an address, an attacker could change the ID of the address to write the data to. If the ID belongs to an address which does not belong to the current logged-in user, every field in the address is set to null. An attacker could use this to null all addresses in a shop.
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