It appears that the meltdown/spectre rabbit hole is deeper and more twisted than we realized. Researchers from Princeton and Nvidia have found two new variants they call MeltdownPrime and SpectrePrime. The good news about these is current software mitigation should prevent any attack using the variants. The bad news is that this finding identifies further hardware corrections that need to be made in future processors. Intel, AMD, and others have got their work cut out for them. You can read the paper here.

In short, the team have discovered new ways for malware to extract sensitive information, such as passwords and other secrets, from a vulnerable computer's memory by exploiting the Meltdown and Spectre design blunders in modern processors. The software mitigations being developed and rolled out to thwart Meltdown and Spectre attacks, which may bring with them performance hits, will likely stop these new exploits.