We contemplated putting together an LWN article on the "microarchitectural data sampling" (MDS) vulnerabilities, as we've done for past speculative-execution issues. But the truth of the matter is that it's really more of the same, and there is a lot of material out there on the net already. So, for those who would like to learn more, here's a list of resources.
This page from the kernel documentation contains a fairly detailed description of the problem and this page has mitigation information. ZombieLoadAttack.com describes the ZombieLoad MDS attack and, in particular, contains this paper [PDF] from Michael Schwarz et al. with the details.
Jon Masters has written an overview article complete with a three-minute video on the vulnerabilities and their exploits. For those wanting more Masters, there is also a longer video that goes deeper. Here is Intel's "deep dive" into the MDS vulnerabilities. Cerberus Technology has put up an overview article that discusses some of the possible attacks enabled by the MDS vulnerabilities.