Apple has confirmed that all Mac systems and iOS devices are affected by Meltdown and Spectre vulnerabilities. At this time they have released mitigations to iOS 11.2, mac OS 10.13.2, and tvOS 11.2 to mitigate the risk of Meltdown on those OS. They plan to release mitgations in the coming days for their browser, Safari. If you haven't updated the aformentioned OS then you might want to do so before exploits are out in the wild. Since exploiting many of these issues requires a malicious app to be loaded on your Mac or iOS device, we recommend downloading software only from trusted sources such as the App Store. Apple has already released mitigations in iOS 11.2, macOS 10.13.2, and tvOS 11.2 to help defend against Meltdown.