The remote Debian host is missing a security-related update.
Two vulnerabilities were discovered in tomcat7, a servlet and JSP engine. - CVE-2017-5647 Pipelined requests were processed incorrectly, which could result in some responses appearing to be sent for the wrong request. - CVE-2017-5648 Some application listeners calls were issued against the wrong objects, allowing untrusted applications running under a SecurityManager to bypass that protection mechanism and access or modify information associated with other web applications.
Upgrade the tomcat7 packages. For the stable distribution (jessie), these problems have been fixed in version 7.0.56-3+deb8u10. For the upcoming stable (stretch) and unstable (sid) distributions, these problems have been fixed in version 7.0.72-3.