The data of hundreds of millions of people has been sold to criminals. More than 180,000 people are affected by the hack.
More than 3 million numbers were hacked in Belgium, France and Portugal. It's not known how the data was obtained, but it's for sale.
"I think this is an attempt at fraud, considering the large amount of phone numbers concerned," he said.
"SCAMmers will try to steal the identities of our contacts: I have a friend on Whatsapp; I receive a message from him; it's his number because he's in my contact list, so no worries, I'll follow up" The goal is to make money.
The phone numbers could be used for fraudulent activities.
What you can do to protect your data
Users should use data security practices to keep their data safe.
The expert says that there is a privacy setting in the app.
Call your friends and use your first name in your profile.
Other tips include using a high-quality virtual private network.
Just listing our first name should suffice.
A quarter of the users are affected. Meta hasn't commented on the hack for the time being.