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.
Apache Struts 2 before 2.3.14.3 allows remote attackers to execute arbitrary OGNL code via a request with a crafted action name that is not properly handled during wildcard matching, a different vulnerability than CVE-2013-2135.
Apache Struts Showcase App 2.0.0 through 2.3.13, as used in Struts 2 before 2.3.14.1, allows remote attackers to execute arbitrary OGNL code via a crafted parameter name that is not properly handled when invoking a redirect.
Allocation of Resources Without Limits or Throttling vulnerability in Apache Software Foundation Apache Struts.This issue affects Apache Struts: through 2.5.30, through 6.1.2. Upgrade to Struts 2.5.31 or 6.1.2.1 or greater.