An improper access control vulnerability in the Azure Managed Instance for Apache Cassandra allows an authenticated attacker to elevate privileges over a network.

When running Apache Cassandra with the following configuration: enableuserdefinedfunctions: true enablescripteduserdefinedfunctions: true enableuserdefinedfunctionsthreads: false it is possible for an attacker to execute arbitrary code on the host. The attacker would need to have enough permissions to create user defined functions in the cluster to be able to exploit this. Note that this configuration is documented as unsafe, and will continue to be considered unsafe after this CVE.

The default configuration in Apache Cassandra 3.8 through 3.11.1 binds an unauthenticated JMX/RMI interface to all network interfaces, which allows remote attackers to execute arbitrary Java code via an RMI request. This issue is a regression of CVE-2015-0225. The regression was introduced in https://issues.apache.org/jira/browse/CASSANDRA-12109. The fix for the regression is implemented in https://issues.apache.org/jira/browse/CASSANDRA-14173. This fix is contained in the 3.11.2 release of Apache Cassandra.

It was discovered that the RMI (Java Remote Method Invocation) server implementation in the JMX (Java Management Extensions) component of OpenJDK did not restrict which classes can be deserialized when deserializing authentication credentials. A remote unauthenticated attacker able to connect to a JMX port could possibly use this flaw trigger deserialization flaws.