The Vector power company has shut down its outage app after thousands of customers unwittingly had their data shared.
The information has been available due to a vulnerability on its outage app.
The app is used so customers can report and be informed about power outages.
Vector chief digital officer Nikhil Ravishankar said the information accessed includes the names, phone numbers and email addresses of customers who reported an outage through the app.
Read more on Radio New Zealand.