If you're running El Capitan, you'll need to upgrade to version 10.11.6 and those running macOS Sierra will need to upgrade to version 10.12.6 to receive the security update.
Some people might be a bit miffed about why Apple left older version of macOS out of the first patch, and such a move could fuel conspiracies around Apple forcing people to move to its latest systems and tech. Although the company had previously released a fix for High Sierra to protect against Meltdown and Spectre, it also released a new update for that version of macOS on Tuesday to address the vulnerability that can be exploited by both of those attacks. The update also fixes issues like a maliciously crafted audio file leading to arbitrary code execution and one where an application could run arbitrary code using kernel privileges.
The update also includes a fix for a bug in the Messages app that listed messages in a different order to which they were received and sent.
Apple's $349 voice-activated HomePod speaker is available to order from Friday
Apple has also said that the multi-room audio feature won't arrive until later this year via a software update . The HomePod will be available in White and Space Grey when it lands, with both sitting at the $349 price mark.
The company then patched the Spectre flaws (CVE-2017-5753 and CVE-2017-5715) in a separate security update released on January 8, 2018, for macOS High Sierra 10.13.2, iOS 11.2.2, and Safari 11.0.2. If you've been suffering from this issue, it's time to install macOS 10.13.3 because the fix for this annoying bug is now available. A patch had already been pushed out for macOS High Sierra, but not everyone is running the latest version.
Once downloaded, an information window will pop up on your screen. If you have multiple Mac computers, we strongly recommend installing on a secondary system. The update comes on the same day that Apple released their iOS 11.2.5 software update.