How to find out in 10 seconds whether your phone number was leaked in the giant Facebook breach that exposed the data of 533 million users

• The data of 533 million Facebook users was leaked to a hacker forum last week.
• The leak included users' phone numbers.
• The website "Have I been pwned" added an update so people can find out if their phone number was leaked.

Online security website "Have I been pwned" has launched a new feature to let users quickly find out whether their phone number was leaked in a giant Facebook data breach.

The personal data of 533 million Facebook users was stolen and placed on a hacking forum on Saturday. The data included their names, email addresses, and phone numbers.

Read more: A top Google security exec predicts major hacks will become more common - and urges firms to band together to protect open source projects

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Website "Have I been pwned" has for a long time allowed people to look up whether their emails or passwords were exposed in past data breaches. But the Facebook breach prompted Troy Hunt, the security analyst who runs the site, to let people search phone numbers too, because the leaked data set contained far more phone numbers than email addresses.

-Troy Hunt (@troyhunt) April 6, 2021

Hunt said in a blog post he had seen "unprecedented" levels of people using "Have I been pwned" since the Facebook breach became public. He said the new update would only apply to phone numbers leaked in the Facebook breach, and not earlier leaks.

To search for a phone number, users will have to use the international format - i.e. with their country and area codes, so a US user would have to add +1 and their area code before their number.