Powerpoint/Excel Macro Vulnerability Question

Does anyone know or have any information on exactly how the latest
Microsoft Powerpoint/Excel marco vulnerability works?

I understand that a flaw exists in the way macros are detected that can
allow a user to bypass macro-checking mechanism and that the
macro-detecting framework fails to detect all instances in which the
macro processor can execute macro commands. But, does anyone know
exactly how it works within the control flow of the software?

Thanks,

Andrew

Andrew G