The Apache Struts REST Plugin is using XStream library which is vulnerable and allow perform a DoS attack when using a malicious request with specially crafted XML payload. Upgrade to the Apache Struts version 2.5.16 and switch to an optional Jackson XML handler as described here http://struts.apache.org/plugins/rest/#custom-contenttypehandlers. Another option is to implement a custom XML handler based on the Jackson XML handler from the Apache Struts 2.5.16.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Struts | Apache | 2.1.1 (including) | 2.5.14.1 (including) |
| Libstruts1.2-java | Ubuntu | trusty | * |