Hi Nancy,
I'm not sure what you're referring to with 'CMS' (that can mean lots of things), but since you're posting in the SAPGUI space I'm guessing you are concerned with desktop office integration in SAPGUI. What release and patch level of SAPGUI are you using? That can have a big impact on what versions of MS Office are supported. Office 365 is a special case, since by default it's a cloud offering, but there are versions that allow local installations equivalent to Office 2013, which is supported as of patch 3 of SAPGUI 7.30 (32-bit only). Also, until patch 7 of GUI 7.30 no 64-bit versions of Office are supported.
The issue with Office 365, being cloud-based, is that it could be upgraded by Microsoft without you necessarily being aware of it, and they might have updated to something that isn't yet supported by SAPGUI.
Full details are in Note 722513: Desktop Office Integration: Maintenance information.
Regards,
Matt