ActionServlet.java in Apache Struts 1 1.x through 1.3.10 does not properly restrict the Validator configuration, which allows remote attackers to conduct cross-site scripting (XSS) attacks or cause a denial of service via crafted input, a related issue to CVE-2015-0899.
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.