Kyuubi Engine UI proxy accepts a host and port from the request path and proxies HTTP requests to that destination. A remote requester with network access to the proxy can cause the Kyuubi server to send HTTP requests to arbitrary reachable hosts, resulting in SSRF or open-proxy behavior. This issue affects Apache Kyuubi: from 1.8.0 before 1.12.0. Users are recommended to upgrade to version 1.12.0, which disables the proxy by default. To restore proxied Engine UI, set kyuubi.frontend.rest.engine.ui.proxy.enabled=true and configure allowed target hosts with kyuubi.frontend.rest.engine.ui.proxy.hosts.