Quest Apartment Hotels is investigating a security breach affecting customer personal data dating from before June 2025, according to an email sent to customers and seen by the Australian Broadcasting Corporation on Wednesday.

"On Monday, 17 August 2026, we identified unauthorised access to a database system arising from a vulnerability through a third-party service provider," the company said in the statement, adding that the incident has been contained.

Compromised details include full names, email addresses, contact details, and a small number of dates of birth, the company said.

"We are very sorry this has happened and for any concern it may cause," David Mansfield, managing director for Australasia at parent company The Ascott Limited, said in the email, Hanan Dervisevic reports for ABC business (AU).