BranchScope is a newly identified side-channel attack that can be used on Skylake, Haswell, and Sandy Bridge CPUs. While a bit off topic, the video below talks about Meltdown and Spectre and how those work that gives a good overview. Dmitry Evtyushkin, one of the people involved in this research, told SecurityWeek that while they have not been tested, the microcode updates released by Intel in response to Meltdown and Spectre might only fix the BTB vector, which means BranchScope attacks could still be possible. However, Intel told the researchers that software guidance for mitigating Spectre Variant 1 could be effective against BranchScope attacks as well.