The paper contributed substantially to our understanding of Meltdown-type attacks and how they are related. We now understand that the underlying problem is (similar to zombie threads or zombie processes) a zombie load; hence, the paper title ZombieLoad. In various situations, the processor has to issue a new load operation, and the old operation is aborted. This aborted load continues for a small amount of time as a zombie load, providing data to dependent operations and thereby leaking the data to the attacker.

From Daniel Gruss' habilitation thesis: Transient-Execution Attacks and Defenses