An attacker submits an XML document to a target application where the XML
						document uses nested entity expansion to produce an excessively large output
						XML. XML allows the definition of macro-like structures that can be used to
						simplify the creation of complex structures. However, this capability can be
						abused to create excessive demands on a processor's CPU and memory. A small
						number of nested expansions can result in an exponential growth in demands
						on memory. For example, consider: