The vulnerability stems from insecure XML parser configuration. While exact code isn't available, the advisory explicitly states the parser wasn't configured to prevent XXE. In Java XML processing, this typically occurs in DocumentBuilderFactory/SAXParserFactory initialization methods where security features aren't set. The deployment package build step's XML processing logic would contain these vulnerable parser initialization routines. The high confidence comes from: 1) The vulnerability type (CWE-611) directly maps to XML parser configuration 2) The patch explicitly mentions disabling external entity resolution 3) Jenkins plugin vulnerabilities of this type commonly manifest in build step processors handling XML input.