Description
In Apache Struts 2.5 through 2.5.5, if an application allows entering a URL in a form field and the built-in URLValidator is used, it is possible to prepare a special URL which will be used to overload server process when performing validation of the URL.
Remediation
References
http://www.securityfocus.com/bid/94657
https://security.netapp.com/advisory/ntap-20180629-0003/
https://struts.apache.org/docs/s2-044.html