In recent news, major CPUs have been dealing with issues known as Meltdown and Spectre. These are vulnerabilities that can allow access to sensitive memory data through software running on the same physical machine, for example, from malware accidentally downloaded by a user.
Affected systems include: all modern Intel processors, machines running Windows, Windows Server, macOS and Linux as well as 'virtualisation' platforms such as VMware and HyperV, and cloud platforms including Amazon Web Services (AWS) and Microsoft Azure. Other platforms and appliances using the affected processors, which may include network and storage systems, may also be at potential risk. The vulnerabilities are serious and, in the case of Spectre, difficult to patch or mitigate.