https://www.theverge.com/2018/1/8/16863884/meltdown-spectre-apple-security-update-safari-webkit

Apple has released three new security updates aimed at protecting Safari and WebKit from the Spectre attack. The three updates make changes to iOS, macOS, and Safari itself, but in each case, the stated goal is protecting Safari and the underlying browser engine against attacks exploiting the recently published Spectre vulnerability.

Few further details are available on the updates, although Apple’s description indicates the purpose of the updates is to protect against Spectre attacks. The researchers responsible for discovering the bug, including Google’s Jann Horn, are thanked in the acknowledgments.