Apache Tomcat is a servlet container for the Java Servlet and JavaServer Pages (JSP) technologies.
A vulnerability was discovered in the error page mechanism in Tomcat's DefaultServlet implementation. A crafted HTTP request could cause undesired side effects, possibly including the removal or replacement of the custom error page. (CVE-2017-5664)
A vulnerability was discovered in Tomcat. When running an untrusted application under a SecurityManager it was possible, under some circumstances, for that application to retain references to the request or response objects and thereby access and/or modify information associated with another web application. (CVE-2017-5648)