Hungry and keen for a Saturday night at home, Ngaire Stevens logged into her Menulog account only to see the food delivery website recognised her as "Beth", then "Letitia" and then "Peter".

A few clicks later, Ms Stevens, with her husband George Carter beside her, realised she could view other Menulog customers' private information, including phone numbers, home addresses and email addresses.

"We live in Fairlight, Sydney, and yet we were seeing what Beth in Melbourne had recently ordered," the early childhood educator said.

"We then clicked on my account details and up came a Letitia in Dulwich Hill with her mobile number, home address and email address, and on navigating to the front page again it said 'Hi Peter' with a list of his recent orders in Melbourne."