If you've stayed at a Starwood Hotel property in recent years, your personal information may have been compromised.

Marriott International announced Friday that hackers had copied data from the reservation database for its Starwood Hotels brand, with unauthorized access dating back to 2014.

"The company has not finished identifying duplicate information in the database, but believes it contains information on up to approximately 500 million guests who made a reservation at a Starwood property," Marriott said in the announcement.

For 327 million guests, they said, the information compromised "includes some combination of" data points including name, mailing address, phone number, email address, passport number and date of birth. Some of those guests may also have had their payment card information compromised.

"For the remaining guests [in that 500 million total], the information was limited to name and sometimes other data such as mailing address, email address, or other information," they said.

The extent of the data stolen makes it important for travelers to take action. (See tips below.)

"The names, addresses, passport numbers and other sensitive personal information that was exposed is of greater concern than the payment info, which was encrypted," CreditCards.com industry analyst Ted Rossman said in a statement. "People should be concerned that criminals could use this info to open fraudulent accounts in their names."

How to freeze your credit report for free: • TransUnion: Visit TransUnion.com/credit-freeze. The company also has a free-freeze mobile app called myTransUnion, available at the Google Play Store and the Apple App Store. • Equifax: Visit https://www.Equifax.com/personal/credit-report-services/. Or call its automated line at 800-685-1111. • Experian: Visit www.Experian.com/freeze. Or call 1-888-EXPERIAN (1-888-397-3742).

Review your credit report and statements for potential fraud. Consider freezing your credit, if other breaches haven't already prompted you to take that step. It's free, and quickly accomplished by reaching out to the three major bureaus.