Marriott announced that about 500 million guests' information may have been accessed through a data security breach involving the Starwood guest reservation database.
The hotel chain said in a press release that on Nov. 19, an investigation determined there was unauthorized access to the database.
An unauthorized party had access to the Starwood network since 2014, the company said.
The breached guest information includes some combination of name, mailing address, phone number, email address, passport number, Starwood Preferred Guest account information, date of birth, gender, arrival and departure information, reservation date and communication preferences.
For some, the information also includes payment card numbers and payment card expiration dates, but the numbers were encrypted.
"We deeply regret this incident happened,” said Arne Sorenson, Marriott’s President and Chief Executive Officer. “We fell short of what our guests deserve and what we expect of ourselves. We are doing everything we can to support our guests, and using lessons learned to be better moving forward.”
Marriott will begin sending emails starting Friday to affected guests. For more information on the breach, click here.