The CycloneDX core module provides a model representation of the SBOM along with utilities to assist in creating, validating, and parsing SBOMs. Before deserializing CycloneDX Bill of Materials in XML format, _cyclonedx-core-java_ leverages XPath expressions to determine the schema version of the BOM. The `DocumentBuilderFactory` used to evaluate XPath expressions was not configured securely, making the library vulnerable to XML External Entity (XXE) injection. This vulnerability has been fixed in cyclonedx-core-java version 9.0.4.
The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.