The vulnerability specifically involves uncontrolled resource consumption through ConditionRefresh requests. OPC UA server implementations typically handle subscription-related operations in Subscription service classes. The ConditionRefresh method would be responsible for processing refresh requests, and the advisory explicitly mentions this as the attack vector. Without proper throttling or resource limits in this handler, repeated requests would accumulate memory allocations. The high confidence comes from the direct correlation between the documented attack vector (ConditionRefresh abuse) and the standard architecture of OPC UA servers.