The Issue

An XML External Entity attack is a type of attack against an application that parses XML input. This attack occurs when XML input containing a reference to an external entity is processed by a weakly configured XML parser. This attack may lead to the disclosure of confidential data, denial of service, server side request forgery, port scanning from the perspective of the machine where the parser is located, and other system impacts.

HAPI FHIR insecurely parses user-supplied XML content within the XLSXmlParser.java file, allowing attackers to perform XXE attacks.

Where the Issue Occurred

Found on line 165 - 168 hapi-fhir/hapi-fhir-utilities/src/main/java/org/hl7/fhir/utilities/XLSXmlParser.java#L165-168:

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setNamespaceAware(true);
DocumentBuilder builder = factory.newDocumentBuilder();
return builder.parse(in);

Disclosure Timeline

• Issue Reported: 24th October 2018
• Blog Post Published: 28th October 2018
• Applied for CVE: