Memory leak in QNetwork on SunOS 5.10 64bit

When running the QT examples "fortuneserver" or "threadedfortuneserver" the server process allocates more an more memory, if QT was build in 64bit mode. If QT is build in 32bit mode, the server process has a constant amount memory allocated. So, only the 64bit build is affected.
It seems, that the server doesn't free some memory after he had processed a client request ( request was send with the fortuneclient example ).

Found in version 4.4.3, 4.5.3 and 4.6.2 .

Memory allocation checked with prstat command ( see attached screenshot ).
There were some requests send from the client to the server between 2 lines of the output in the screenshot.