From POCO Forum:

Postby hitxp » Sun Feb 01, 2015 4:56 am

in source file "poco-1.6.0/Net/samples/EchoServer/src/EchoServer.cpp"
line 119 "_fifoIn.drain(_fifoOut.write(_fifoIn.buffer()));"
I believe it should be changed to "_fifoIn.drain(_fifoOut.write(_fifoIn.buffer(), fifoIn.used()));" to avoid copying the whole buffer which will lead to a bug.