Facebook will contact 87 million users on Monday to inform them their data was leaked to Cambridge Analytica, The Guardian reported.
The majority of affected users – 70 million – are from the United States.
In South Africa, 59,777 users were potentially impacted.
Countries like the UK, Philippines, and Indonesia have over a million people each who may have had their personal information harvested.
All 2.2 billion users on Facebook will also receive a “Protecting Your Information” notice. It will include a link to see what apps you use and what information has been shared with those apps.
From there, Facebook will let you turn off apps individually, or disable third-party access.