I get this errors constantly in my server when a web connection is interrupted from the browser for instance:

11:50:45,301 ERROR [stderr] (default task-339) Exception in thread "default task-339" java.nio.BufferOverflowException
11:50:45,301 ERROR [stderr] (default task-339) at java.nio.DirectByteBuffer.put(DirectByteBuffer.java:363)
11:50:45,301 ERROR [stderr] (default task-339) at java.nio.ByteBuffer.put(ByteBuffer.java:859)
11:50:45,301 ERROR [stderr] (default task-339) at io.undertow.util.HttpString.appendTo(HttpString.java:204)
11:50:45,301 ERROR [stderr] (default task-339) at io.undertow.server.protocol.http.HttpResponseConduit.processWrite(HttpResponseConduit.java:150)
11:50:45,301 ERROR [stderr] (default task-339) at io.undertow.server.protocol.http.HttpResponseConduit.flush(HttpResponseConduit.java:629)
11:50:45,301 ERROR [stderr] (default task-339) at io.undertow.conduits.AbstractFixedLengthStreamSinkConduit.flush(AbstractFixedLengthStreamSinkConduit.java:205)
11:50:45,301 ERROR [stderr] (default task-339) at org.xnio.conduits.ConduitStreamSinkChannel.flush(ConduitStreamSinkChannel.java:162)
11:50:45,301 ERROR [stderr] (default task-339) at io.undertow.channels.DetachableStreamSinkChannel.flush(DetachableStreamSinkChannel.java:100)
11:50:45,301 ERROR [stderr] (default task-339) at io.undertow.server.HttpServerExchange.closeAndFlushResponse(HttpServerExchange.java:1489)
11:50:45,317 ERROR [stderr] (default task-339) at io.undertow.server.HttpServerExchange.endExchange(HttpServerExchange.java:1470)
11:50:45,317 ERROR [stderr] (default task-339) at io.undertow.server.Connectors.executeRootHandler(Connectors.java:201)
11:50:45,317 ERROR [stderr] (default task-339) at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:727)
11:50:45,317 ERROR [stderr] (default task-339) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
11:50:45,317 ERROR [stderr] (default task-339) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
11:50:45,317 ERROR [stderr] (default task-339) at java.lang.Thread.run(Thread.java:745)

And then, I think this errors lead to a OutOfMemory crash:

14:23:09,592 ERROR [org.xnio.listener] (default I/O-3) XNIO001007: A channel event listener threw an exception: java.lang.OutOfMemoryError
at sun.misc.Unsafe.allocateMemory(Native Method) [rt.jar:1.8.0_20]
at java.nio.DirectByteBuffer.<init>(DirectByteBuffer.java:127) [rt.jar:1.8.0_20]
at java.nio.ByteBuffer.allocateDirect(ByteBuffer.java:311) [rt.jar:1.8.0_20]
at org.xnio.BufferAllocator$2.allocate(BufferAllocator.java:57) [xnio-api-3.2.2.Final.jar:3.2.2.Final]
at org.xnio.BufferAllocator$2.allocate(BufferAllocator.java:55) [xnio-api-3.2.2.Final.jar:3.2.2.Final]
at org.xnio.ByteBufferSlicePool.allocate(ByteBufferSlicePool.java:149) [xnio-api-3.2.2.Final.jar:3.2.2.Final]
at org.xnio.ssl.JsseSslConduitEngine.<init>(JsseSslConduitEngine.java:143) [xnio-api-3.2.2.Final.jar:3.2.2.Final]
at org.xnio.ssl.JsseSslStreamConnection.<init>(JsseSslStreamConnection.java:71) [xnio-api-3.2.2.Final.jar:3.2.2.Final]
at org.xnio.ssl.JsseAcceptingSslStreamConnection.accept(JsseAcceptingSslStreamConnection.java:45) [xnio-api-3.2.2.Final.jar:3.2.2.Final]
at org.xnio.ssl.JsseAcceptingSslStreamConnection.accept(JsseAcceptingSslStreamConnection.java:37) [xnio-api-3.2.2.Final.jar:3.2.2.Final]
at org.xnio.ssl.AbstractAcceptingSslChannel.accept(AbstractAcceptingSslChannel.java:187) [xnio-api-3.2.2.Final.jar:3.2.2.Final]
at org.xnio.ChannelListeners$10.handleEvent(ChannelListeners.java:289) [xnio-api-3.2.2.Final.jar:3.2.2.Final]
at org.xnio.ChannelListeners$10.handleEvent(ChannelListeners.java:286) [xnio-api-3.2.2.Final.jar:3.2.2.Final]
at org.xnio.ChannelListeners.invokeChannelListener(ChannelListeners.java:92) [xnio-api-3.2.2.Final.jar:3.2.2.Final]
at org.xnio.ChannelListeners$DelegatingChannelListener.handleEvent(ChannelListeners.java:1092) [xnio-api-3.2.2.Final.jar:3.2.2.Final]
at org.xnio.ChannelListeners.invokeChannelListener(ChannelListeners.java:92) [xnio-api-3.2.2.Final.jar:3.2.2.Final]
at org.xnio.nio.NioTcpServerHandle.handleReady(NioTcpServerHandle.java:53) [xnio-nio-3.2.2.Final.jar:3.2.2.Final]
at org.xnio.nio.WorkerThread.run(WorkerThread.java:539) [xnio-nio-3.2.2.Final.jar:3.2.2.Final]

This is the trace for version 8.2 of WildFly:

17:17:16,957 ERROR [io.undertow.request] (default task-49) Undertow request failed HttpServerExchange

: java.nio.BufferOverflowException
at java.nio.DirectByteBuffer.put(DirectByteBuffer.java:363) [rt.jar:1.8.0_20]
at java.nio.ByteBuffer.put(ByteBuffer.java:859) [rt.jar:1.8.0_20]
at io.undertow.util.HttpString.appendTo(HttpString.java:204)
at io.undertow.server.protocol.http.HttpResponseConduit.processWrite(HttpResponseConduit.java:166)
at io.undertow.server.protocol.http.HttpResponseConduit.write(HttpResponseConduit.java:564)
at io.undertow.conduits.AbstractFixedLengthStreamSinkConduit.write(AbstractFixedLengthStreamSinkConduit.java:106)
at org.xnio.conduits.Conduits.writeFinalBasic(Conduits.java:132) [xnio-api-3.3.0.Final.jar:3.3.0.Final]
at io.undertow.conduits.AbstractFixedLengthStreamSinkConduit.writeFinal(AbstractFixedLengthStreamSinkConduit.java:175)
at org.xnio.conduits.ConduitStreamSinkChannel.writeFinal(ConduitStreamSinkChannel.java:104) [xnio-api-3.3.0.Final.jar:3.3.0.Final]
at io.undertow.channels.DetachableStreamSinkChannel.writeFinal(DetachableStreamSinkChannel.java:194)
at io.undertow.server.HttpServerExchange$WriteDispatchChannel.writeFinal(HttpServerExchange.java:1829)
at io.undertow.servlet.spec.ServletOutputStreamImpl.writeBufferBlocking(ServletOutputStreamImpl.java:565)
at io.undertow.servlet.spec.ServletOutputStreamImpl.close(ServletOutputStreamImpl.java:600)
at io.undertow.servlet.spec.HttpServletResponseImpl.closeStreamAndWriter(HttpServletResponseImpl.java:497)
at io.undertow.servlet.spec.HttpServletResponseImpl.responseDone(HttpServletResponseImpl.java:581)
at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:308)
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:247)
at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:76)
at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:166)
at io.undertow.server.Connectors.executeRootHandler(Connectors.java:197)
at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:759)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [rt.jar:1.8.0_20]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [rt.jar:1.8.0_20]
at java.lang.Thread.run(Thread.java:745) [rt.jar:1.8.0_20]

10:57:12,389 ERROR [org.xnio.listener] (default I/O-4) XNIO001007: A channel event listener threw an exception: java.lang.OutOfMemoryError
at sun.misc.Unsafe.allocateMemory(Native Method) [rt.jar:1.8.0_20]
at java.nio.DirectByteBuffer.<init>(DirectByteBuffer.java:127) [rt.jar:1.8.0_20]
at java.nio.ByteBuffer.allocateDirect(ByteBuffer.java:311) [rt.jar:1.8.0_20]
at org.xnio.BufferAllocator$2.allocate(BufferAllocator.java:57) [xnio-api-3.3.0.Final.jar:3.3.0.Final]
at org.xnio.BufferAllocator$2.allocate(BufferAllocator.java:55) [xnio-api-3.3.0.Final.jar:3.3.0.Final]
at org.xnio.ByteBufferSlicePool.allocate(ByteBufferSlicePool.java:143) [xnio-api-3.3.0.Final.jar:3.3.0.Final]
at org.xnio.ssl.JsseSslConduitEngine.<init>(JsseSslConduitEngine.java:146) [xnio-api-3.3.0.Final.jar:3.3.0.Final]
at org.xnio.ssl.JsseSslStreamConnection.<init>(JsseSslStreamConnection.java:71) [xnio-api-3.3.0.Final.jar:3.3.0.Final]
at org.xnio.ssl.JsseAcceptingSslStreamConnection.accept(JsseAcceptingSslStreamConnection.java:45) [xnio-api-3.3.0.Final.jar:3.3.0.Final]
at org.xnio.ssl.JsseAcceptingSslStreamConnection.accept(JsseAcceptingSslStreamConnection.java:37) [xnio-api-3.3.0.Final.jar:3.3.0.Final]
at org.xnio.ssl.AbstractAcceptingSslChannel.accept(AbstractAcceptingSslChannel.java:187) [xnio-api-3.3.0.Final.jar:3.3.0.Final]
at org.xnio.ChannelListeners$10.handleEvent(ChannelListeners.java:289) [xnio-api-3.3.0.Final.jar:3.3.0.Final]
at org.xnio.ChannelListeners$10.handleEvent(ChannelListeners.java:286) [xnio-api-3.3.0.Final.jar:3.3.0.Final]
at org.xnio.ChannelListeners.invokeChannelListener(ChannelListeners.java:92) [xnio-api-3.3.0.Final.jar:3.3.0.Final]
at org.xnio.ChannelListeners$DelegatingChannelListener.handleEvent(ChannelListeners.java:1092) [xnio-api-3.3.0.Final.jar:3.3.0.Final]
at org.xnio.ChannelListeners.invokeChannelListener(ChannelListeners.java:92) [xnio-api-3.3.0.Final.jar:3.3.0.Final]
at org.xnio.nio.NioTcpServerHandle.handleReady(NioTcpServerHandle.java:53) [xnio-nio-3.3.0.Final.jar:3.3.0.Final]
at org.xnio.nio.WorkerThread.run(WorkerThread.java:539) [xnio-nio-3.3.0.Final.jar:3.3.0.Final]