Apache Struts is a free and open-source framework used to build Java web applications. The use of Object Graph Navigation Language (OGNL) expressions in the Apache Struts smooth the way for attackers to execute arbitrary code remotely. On sending a malicious Content-Type, Content-Disposition, or Content-Length HTTP header with a Content-Type header containing a #cmd= string an incorrect exception handling and error message will be generated as the Jakarta Multipart parser fails to validate the file-upload attempts. This permits remote attackers to execute arbitrary commands on the vulnerable servers.