You can manually go up in the inheritance chain to get the base fields:
Given these classes:
class SuperClass1
{
private int myField;
}
class SuperClass2 : SuperClass1
{
}
class MyClass : SuperClass2
{
}
This should work:
var myObj = new MyClass();
var myField = typeof(MyClass).BaseType
.BaseType
.GetField("myField", BindingFlags.Instance | BindingFlags.NonPublic);
There’s a more generic solution in this SO answer: Not getting fields from GetType().GetFields with BindingFlag.Default