The Meltdown and Spectre security flaws are certainly scary, but there are reasons to be leery of the various updates intended to mitigate them. Even if you aren't affected by the performance hit these updates can produce (leading some folks to refer to the patches as "SpecDown"), you could be at risk of suffering random reboots. Fortunately, Intel's now identified the cause of those restarts, at least for Haswell and Broadwell machines.
Unfortunately, identifying the root cause means a new round of patches is in the works for Haswell and Broadwell systems. The company says it has a new patch nearly ready for systems with those CPUs that offers mitigation against the Spectre vulnerability and comes without risk of random restarts. Newer Intel platforms could still experience stability problems with today's appropriate microcode patches installed, though, and owing to the stability issues that have cropped up, Intel recommends that all users of Haswell and newer platforms should stop installing the most recent microcode or firmware updates already in the wild in anticipation of a fixed fix.
Intel will be supplying the patched patches for Haswell and Broadwell CPUs to OEMs and component vendors, not directly to end users. It will be up to those companies to get the patches into the hands of us regular folks in the form of firmware updates. Intel says it will share details on exact timing of the updates' release later this week. The company didn't say anything about a timeline for patches for pre- or post-Haswell and Broadwell CPUs, though. Folks with those chips will have longer yet to wait.