WhatsApp is urging people to update the app immediately after it was targeted by hackers installing sophisticated spyware on users' phones, giving them access to a trove of data.

The security vulnerability has been fixed in updated versions of WhatsApp released in recent days, but some users will need to manually update the app to get protected.

It is not yet known how many of WhatsApp's 1.5 billion users were targeted by the bad actors, who installed the surveillance technology - developed by Israel's NSO Group - by phoning the target through WhatsApp's call functionality.

Facebook, which owns WhatsApp, said: "WhatsApp encourages people to upgrade to the latest version of our app, as well as keep their mobile operating system up to date, to protect against potential targeted exploits designed to compromise information stored on mobile devices."

Scroll on to find out how to make sure your phone is safe.

First, check to see if you have the latest version of WhatsApp. Let's start with Android.

  • Open Play Store
  • Go to the Menu
  • Tap 'My apps & games'
  • Find WhatsApp Messenger within your 'Installed' apps
  • Tap the app
  • Hit 'Read more' and scroll to the bottom

Under 'App info,' if it says you have version 2.19.134, good news! Your phone is protected.

If you have an earlier version, for example 2.19.133, you need to update.

Now to get updating.

  • Go to Play Store
  • Tap the Menu
  • Hit 'My apps & games'
  • Tap 'Update' next to the WhatsApp Messenger

Alternatively, you can search for WhatsApp in the Play Store and hit 'Update.'

Remember, you want to make sure the app updates to version 2.19.134. The screenshot above shows what the app looks like once updated.

Here's how to check your version of WhatsApp if you have an iPhone.

  • Open the App Store
  • Tap the 'Updates' tab
  • Scroll until you see WhatsApp, either under 'Pending' or 'Updated recently'
  • Hit 'More' to see your most recent version number

If you have version 2.19.51, again, you're in luck!

However, if you have version 2.19.50 like the screenshot above, you need to update the latest version.

Finally, here's how to update WhatsApp on your iPhone.

  • Open the App Store
  • Tap 'Updates'
  • Find WhatsApp Messenger and hit 'Update'

Alternatively, you can search for WhatsApp in the App Store and hit 'Update.' You want version 2.19.51 to be protected.

And that's it, you should be safe from the hackers.

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