HtmlUnit is a GUI-less browser for Java programs. HtmlUnit is vulnerable to Remote Code Execution (RCE) via XSTL, when browsing the attacker’s webpage. This vulnerability has been patched in version 3.9.0
https://www.htmlunit.org/changes-report.html#a3.9.0
https://github.com/HtmlUnit/htmlunit/security/advisories/GHSA-37vq-hr2f-g7h7