Some critical vulnerabilities have been reported in Apache Tomcat, which can be exploited by malicious people to bypass certain security restrictions and cause a DoS (Denial of Service) attack. The actual impact varies significantly depending on the design and purpose of the affected application. If you are affected, Please update your Tomcat to a fixed version i.e.guiTomcat 7.x.x: Update to version 7.0.32.32. Tomcat 6.x and Tomcat.
Source: https://thehackernews.com/2012/12/apache-tomcat-multiple-critical.html