Apple has admitted that all Mac and iOS devices – including iPhones, iPads and Macs – are affected by the so-called Meltdown and Spectre security flaws, which could give hackers access to users' data.
How can you protect your devices from the bug? Here's what you need to know.
What are Meltdown and Spectre?
Two major vulnerabilities in chips designed by UK giant Arm and its US rival Intel have been discovered by security experts. The flaws affect your device's speculative execution, which tries to speed up processing by predicting which tasks it will be asked to perform. They allow hackers to force your device's memory to perform unnecessary operations, giving them sight of sensitive data.
Which Apple devices are affected?
Overnight, Apple admitted the flaws apply to chips used in all its Mac and iOS devices – so Mac computers, iPhones, iPads and Apple TVs. The only exemption is the Apple Watch.
How can I protect my Apple devices?
Apple pointed out that it hasn't spotted anyone exploiting the vulnerabilities yet, and added it has already released updates protecting users against Meltdown in iOS11.2, MacOS 10.13.2 and tvOS 11.2. In the "coming days", it plans to release a patch against Spectre, in the form of an update to Safari.
In the meantime, as any exploits would come through malicious apps, it warned users only to download apps from the App Store, which has a rigorous approval process.
Read more: Apple apologises for deliberately slowing down older iPhones
What to do