Apache Struts2 Showcase Skill Name Remote Code Execution Vulnerability

This host is running Apache Struts Showcase and is prone to java method execution vulnerability.
Successful exploitation could allow an attacker to execute arbitrary java method. Further that results to disclose environment variables or cause a denial of service or an arbitrary OS command can be executed. Impact Level: System/Application
No solution or patch was made available for at least one year since disclosure of this vulnerability. Likely none will be provided anymore. General solution options are to upgrade to a newer release, disable respective features, remove the product or replace the product by another one.
The flaw is due to an improper validation of user data passed to the 'skillName' parameter in 'edit' and 'save' actions.
Apache Struts2 (Showcase) version and prior