XML External Entity Reference in Apache NiFi

The ExtractCCDAAttributes Processor in Apache NiFi 1.2.0 through 1.19.1 does not restrict XML External Entity references. Flow configurations that include the ExtractCCDAAttributes Processor are vulnerable to malicious XML documents that contain Document Type Declarations with XML External Entity references. The resolution disables Document Type Declarations and disallows XML External Entity resolution in the ExtractCCDAAttributes Processor.