Ticketfly.com says it suffered a "malicious cyber attack" and that names, addresses, email addresses and phone numbers of 27 million accounts were accessed.
In a statement posted on its website, the online ticket booker said account passwords, debit and credit card information was not accessed.
"It’s important to note that many people purchase tickets with multiple email accounts, so the number of individuals impacted is likely lower," the statement said.
— Ticketfly (@ticketfly) June 7, 2018
Ticketfly took its website offline over the weekend after learning of the security breach and forced users to change their passwords. The website is back online.
They are encouraging those who may not have logged in over the weekend to change their passwords.
"To both our clients and fans, we love you. Thank you for your incredible patience and bearing with us over the past days," the company said. "We recognize this has been both frustrating and challenging, and we regret any disruption this has caused."
People can visit support.ticketfly.com for updates.