An attacker corrupts or modifies the content of XML schema information
						passing between client and server for the purpose of undermining the
						security of the target. XML Schemas provide the structure and content
						definitions for XML documents. Schema poisoning is the ability to manipulate
						a schema either by replacing or modifying it to compromise the programs that
						process documents that use this schema. Possible attacks are denial of
						service attacks by modifying the Schema so that it does not contain required
						information for subsequent processing. For example, the unaltered schema may
						require a @name attribute in all submitted documents. If the attacker
						removes this attribute from the schema then documents create using the new
						grammar will lack this field, which may cause the processing application to
						enter an unexpected state or record incomplete data. In addition,
						manipulation of the data types described in the schema may affect the
						results of calculations taken by the document reader. For example, a float
						field could be changed to an int field. Finally, the attacker may change the
						encoding defined in the schema for certain fields allowing the contents to
						bypass filters that scan for dangerous strings. For example, the modified
						schema might us a URL encoding instead of ASCII, and a filter that catches a
						semicolon (;) might fail to detect its URL encoding (%3B).