There is one CPU that exposes its out of order inner workings, the VIA C3 ("ALTINST"). The unintended effects are so bad that people that accidentally discovered it referred to it as a backdoor: https://en.wikipedia.org/wiki/Alternate_Instruction_Set
> "In 2018 Christopher Domas discovered that some Samuel 2 processors came with the Alternate Instruction Set enabled by default and that by executing AIS instructions from user space, it was possible to gain privilege escalation from Ring 3 to Ring 0.["
Because it was implemented in a flawed way.
> "In 2018 Christopher Domas discovered that some Samuel 2 processors came with the Alternate Instruction Set enabled by default and that by executing AIS instructions from user space, it was possible to gain privilege escalation from Ring 3 to Ring 0.["