https://www.bleepingcomputer.com/news/security/researchers-detail-new-cpu-side-channel-attack-named-spectrersb/

Academics from the University of California, Riverside (UCR) have published details last week about a new Spectre-class attack that they call SpectreRSB.

Just like all "Spectre-class" attacks, SpectreRSB takes advantage of the process of speculative execution— a feature found in all modern CPUs that has the role of improving performance by computing operations in advance and later discarding unneeded data.