Hi Rune,
Buffer overflows are not a common problem in .NET applications in general, that is an issue that is very common in the C programming language because developers have to manage use of memory very carefully to prevent the possibility of buffer overflows.
In C# and in .NET in general the runtime manages memory and we do not have to deal directly with memory management from application code. I've never heard of buffer overflows in .NET applications in general unless they are also using some unmanaged code from non-.NET dlls.
I certainly don't see buffer overflows as a risk factor in using mojoPortal and have never encountered one in many years of development of mojoPortal.
Hope it helps,
Joe