In Apache RocketMQ 4.2.0 to 4.6.0, when the automatic topic creation in the broker is turned on by default, an evil topic like “../../../../topic2020” is sent from rocketmq-client to the broker, a topic folder will be created in the parent directory in brokers, which leads to a directory traversal vulnerability. Users of the affected versions should apply one of the following: Upgrade to Apache RocketMQ 4.6.1 or later.