When you applied the hotfix, did it properly update the /LIB directory for the CMS? I'd start there and see what the version numbers are. Technically speaking, when you build the CMS, it copies the /LIB directory files into the /CMS/bin directory. So if you did a clean or rebuild, that should clean the CMS up assuming your /LIB directory has the proper files in it.
For the MVC project, simply referencing the proper nuget package and rebuilding will resolve that issue.