Apache PDFBox 2.0.14 does not properly initialize the XML parser, which allows context-dependent attackers to conduct XML External Entity (XXE) attacks via a crafted XFDF.
https://www.oracle.com/security-alerts/cpuoct2021.html
https://www.oracle.com/security-alerts/cpuapr2020.html
https://www.oracle.com/security-alerts/cpuApr2021.html