The magazine claims that Intel has already been alerted to the problem but so far details of the problems are under wraps.
C't calls the bugs "Spectre Next Generation" and said that it has verified the facts but won't publish the details in case vendors ready security updates.
While c't claims there is “initial evidence” that some ARM CPUs are also affected, that hasn't been verified. Nor is it clear whether AMD CPUs are affected.
You can read the whole story here.