The Meltdown and Spectre attacks that use processor speculative execution to leak sensitive information have resulted in a wide range of software changes to try to limit the scope for harm. Many of these are operating system-level fixes, some of which depend on processor microcode updates.
But Spectre isn’t a simple attack to solve; operating system changes help a great deal, but application-level changes are also needed. Apple has talked about some of the updates it has made to the WebKit rendering engine, used in its Safari browser, but this is only a single application.
Source:: Arstechnica – Gadgets