There is an update of Linux kernel of the 4.15.x – 4.15.2 available in Sparky repos.

The biggest change, comparing to 4.15.1 is patching the Spectre issue (v1).

The Sparky’s Linux kernel is available in Sparky “unstable” repository, so enabled it to upgrade (if you have older version already installed) or to make fresh installation:
https://sparkylinux.org/wiki/doku.php/repository

Follow the Wiki page: https://sparkylinux.org/wiki/doku.php/linux_kernel to install the latest Sparky’s Linux kernel.

It requires rebooting to take effects.

So, looks like the Meltdown (CVE-2017-5754), Spectre v1 (CVE-2017-5753) & v2 (CVE-2017-5715) issues are patched in the latest kernel now.

How to check your present Linux kernel of the Meltdown and Spectre issues?
1. Install ‘spectre-meltdown-checker’ package from Debian’s repository:
sudo apt update
sudo apt install spectre-meltdown-checker

and run it:
sudo spectre-meltdown-checker
This is a screenshot of the checker from my Sparky 5 / Debian testing “Buster” amd64 OS.

Spectre & Meltdown checker