Cunard Cruise Line recently sent an e-mail to an unknown number of its customers that included an attachment containing 1,225 cruise passengers' contact information. Following the error, the company's online booking system was shut down.

The issue was first disclosed on the message boards of Web site Cruise Critic.

"Cruise Critic first became aware of the breach when member davyjones posted on the message boards that he'd received an e-mail with a spreadsheet attachment containing the contact information of 1,225 Cunard passengers," writes Cruise Critic's Dori Saltzman. "The information in the spreadsheet included booking reference numbers, names and email addresses. Passport information was not sent out, a Cunard spokeswoman confirmed. However, it would theoretically be possible to access individuals' passport information using the booking reference numbers, names and email addresses."

"It is unknown how many recipients were sent the spreadsheet," writes Tnooz's Kevin May. "Cunard moved quickly to calm passengers after word leaked out about the security mess-up, with many passengers contacted again and advised to change their booking numbers immediately via the operator’s online trip management system."