Close, Lax, but not quite right. On mobile devices it was the Spectre malware. . . not Meltdown.
That predictive-processing backdoor had very limited capabilities. . . especially on ARM processor based mobile devices. Was it a danger? Yes. Did it have the capability to process large, complex apps? No, only specific functions that were likely to be called next in reference to what was being calculated currently and results cached. That process could hijacked for similarly small processes. The entire app sized processes could not be used.
Yet you still KNOW, this was an NSA back door.