Google has acknowledged a major security issue with its new Pixel 4 smartphone and how it unlocks by scanning its owner's face.

But the company has said, somewhat vaguely, how the update will be released "in the coming months," and not sooner.

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Announced last week, the Pixel 4 smartphone is due to go on sale on October 24, and features a new face unlock system which replaces the fingerprint reader of the year-old Pixel 3. This system works in a very similar way to the iPhone, where infrared light is used to create a 3D map of the owner's face; only when this precise map is recognized, will the phone unlock.

Pre-order Pixel 4 and 4 XL at Best Buy Here

This is supposed to be a more secure form of biometric security than a fingerprint reader, and it is better than using a regular visible light camera to recognize a user's face, as those systems can be tricked with a photograph.

The problem is, the Pixel 4's face unlock system works when the owner's eyes are closed. This potentially means a thief could steal someone's Pixel 4 while they are asleep, then point the phone at their face to unlock it. As demonstrated by BBC reporter Chris Fox, the system could also potentially work if the owner is dead.

Apple includes a system where iPhones do not unlock using Face ID unless the owner's eyes are open. Such a feature was included in pre-production versions of the Pixel 4, but was missing in phones demonstrated at the launch event and will not be included when the phone goes on sale later this week.

In a statement sent to GearBrain, Google said: "We've been working on an option for users to require their eyes to be open to unlock the phone, which will be delivered in a software update in the coming months." A photo of a Pixel 4 leaked online before the phone was announced showed such an option, but that is missing from the retail version.

Pre-order Pixel 4 and 4 XL at Best Buy Here

In the meantime, Google suggests Pixel 4 owners receiving their phones this week enable 'lockdown'. To do this, open the Settings app then navigate to Display -> Advanced -> Lock screen display. If that doesn't work, Google says to navigate to Security & location -> Lock screen preferences.

Switching on lockdown mode adds a new button, labeled 'lockdown,' to the options which appear with a long press of the power/lock button.

Tapping this locks the phone and disables the face scan system, meaning you'll need to enter a PIN, pattern or password to get back in. To keep using lockdown, you need to press and hold the power button then tap the icon every time you lock the phone.

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