Update: Apple Watch is unaffected by both Meltdown and Spectre.
Security researchers have recently uncovered security issues known
by two names, Meltdown and Spectre. These issues apply to all
modern processors and affect nearly all computing devices and
operating systems. All Mac systems and iOS devices are affected,
but there are no known exploits impacting customers at this time.
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. Apple Watch is not
affected by either Meltdown or Spectre. In the coming days we plan
to release mitigations in Safari to help defend against Spectre.
We continue to develop and test further mitigations for these
issues and will release them in upcoming updates of iOS, macOS,