OPC UA Legacy Java Stack is a legacy support for the Java version of OPC UA from the OPC Foundation in the U.S. A denial of service vulnerability exists in OPC UA Legacy Java Stack version 2022-04-01, which stems from improper handling of a large number of message requests, and could be exploited by a remote attacker to cause the server to stop processing messages by sending a by sending a specially crafted message that exhausts available resources to cause the server to stop processing the message.