Comment by grumpymuppet

This kind of thing is a constant worry of mine, but I've never had the (mis?)fortune to look at this particular code.

Signatures/verification (typically) only provide a boolean guard on what you want to be controlled behavior.

To properly protect against cla controlled behavior, the check must be incorporated into the EXECUTION of the behavior (with a safe fail).

This is hard and I think a lot of pentesters will continue to have lucrative work hunting issues like this down for a long time.

Fundamentally, the problem is the "type" of the verification and the execution.