Apache Struts 2 is an open-source Web application framework for developing Java EE Web applications. It uses and extends the Java Servlet API to encourage developers to adopt a model-view-controller (MVC) architecture. OGNL expression injection vulnerabilities may exist in the use of certain tags, resulting in remote code execution. This rule supports to defend the A6: Vulnerable and Outdated Components of OWASP Top 10 - 2021. Other reference:None