I'm using TBinaryProtocol and a simple transport that reads from a given byte array.
C# library contains the following code in TProtocolUtil.Skip(TProtocol prot, TType type):
The type of elements is detected in ReadListBegin(), and, as Skip() does nothing for unknown types, the position in the binary remains the same until the for loop completes.
So, when you try to deserialize invalid data, and a field type happens to be detected as TType.List, you may end up waiting for a random period of time until deserialization is completed (734707176 iterations of skipping in my case).
I suggest throwing an exception immediately when list elements type is unknown. May be, it would be good to have a setting like FailOnUnknownType, so that Skip() will throw instead of ignoring.