The breach may have “impacted” Ticketek Australia customers’ names, dates of birth, and email addresses, which were stored in a cloud-based platform hosted by a third party, it said in a statement late on Friday.
The firm did not say how many people were affected but the government said the incident may have impacted “many Australians”.
Ticketek said passwords and its online payment system were securely encrypted and had not been compromised.
The company had put “every resource” into investigating the incident over the past few days, it said.
“We have already commenced notifying those customers who may have been impacted,” the company added.
“We apologise for any concern that this news may cause – we will provide further updates as more information becomes available.”
Home affairs minister Clare O’Neil said information so far “indicates that this is a breach potentially affecting many Australians”.
She confirmed the hack was likely limited to names, dates of birth, and email addresses.
“Where companies hold a significant amount of data, Australians expect that they look after it,” O’Neil said.
National cyber security coordinator Michelle McGuiness welcomed Ticketek’s “timely approach” to informing customers.
Australia’s federal police and the Australian Signals Directorate were also aware of the incident, she said in a message on social media.
Ticketek is a separate company from California-based concert booking site Ticketmaster, which was revealed this week to be the victim of a potentially major data breach.
A hacking group known as ShinyHunters claimed to have accessed the information of 560 million Ticketmaster customers around the world.
The well-known hacking group posted evidence on May 27 of the hack on the dark web, according to a screenshot shared widely on social media.
The group demanded a ransom payment of US$500,000.
In a filing with the US Securities and Exchange Commission, Ticketmaster’s parent company, Live Nation Entertainment, said on Friday that it had “identified unauthorized activity within a third-party cloud database environment”.