Orome1 quotes a report from Help Net Security: A critical vulnerability in Apache Struts 2 is being actively and heavily exploited, even though the patch for it has been released on Monday. The vulnerability (CVE-2017-5638) affects the Jakarta file upload Multipart parser in Apache Struts 2. It allows attackers to include code in the "Content-Type" header of an HTTP request, so that it is executed by the web server. Almost concurrently with the release of the security update that plugs the hole, a Metasploit module for targeting it has been made available. Unfortunately, the vulnerability can be easily exploited as it requires no authentication, and two very reliable exploits have already been published online. Also, vulnerable servers are easy to discover through simple web scanning. "Struts 2 is a Java framework that is commonly used by Java-based web applications," reports SANS ISC in their blog. "It is also known as 'Jakarta Struts' and 'Apache Struts.' The Apache project currently maintains Struts." Cisco Talos also has a blog detailing the attack.