Denial of Service via incomplete cleanup vulnerability in Apache Tomcat. It was possible for WebSocket clients to keep WebSocket connections open leading to increased resource consumption.This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.0-M16, from 10.1.0-M1 through 10.1.18, from 9.0.0-M1 through 9.0.85, from 8.5.0 through 8.5.98. Users are recommended to upgrade to version 11.0.0-M17, 10.1.19, 9.0.86 or 8.5.99 which fix the issue.