Several issues were discovered in the Tomcat servlet and JSP engine, which could result in session fixation attacks, information disclosure, cross- site scripting, denial of service via resource exhaustion and insecure redirects.
For the oldstable distribution (stretch), these problems have been fixed in version 8.5.50-0+deb9u1. This update also requires an updated version of tomcat-native which has been updated to 1.2.21-1~deb9u1.
We recommend that you upgrade your tomcat8 packages.
Further information about Debian Security Advisories, how to apply these updates to your system and frequently asked questions can be found at: https://www.debian.org/security/