The personal data of 15,497 customers was leaked from a reservation system used by Hotel Kämp and the F6 hotel in a February breach, according to the Nordic Hotels & Resorts company.
"The reservation system of one of our suppliers' websites was compromised. The attack affected two of our hotels," said Jonathan Blom, Nordic Hotels & Resorts' Communications Advisor.
He added that the system attack also affected several other hotels in Finland, but said he did not know which ones, as such arrangements are kept between hotels and the supplier.
The attack took place between 10 and 14 February, according to the firm, which said it became aware of the data breach on 9 April.
Blom said that the vulnerability that enabled the data to be hacked has since been patched.
"We try to work closely with our suppliers and IT support team to prevent things like this from happening, but unfortunately there are criminals who commit crimes to access data. The safety and security of our guests is our top priority," Blom said.
Finnish news outlet MTV first reported about the data breach.
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