Describe CVE-2021-27738.
What is CVE-2021-27738?
All request mappings in `StreamingCoordinatorController.java` handling `/kylin/api/streaming_coordinator/*` REST API endpoints did not include any security checks, which allowed an unauthenticated user to issue arbitrary requests, such as assigning/unassigning of streaming cubes, creation/modification and deletion of replica sets, to the Kylin Coordinator. For endpoints accepting node details in HTTP message body, unauthenticated (but limited) server-side request forgery (SSRF) can be achieved. This issue affects Apache Kylin Apache Kylin 3 versions prior to 3.1.2..