The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly, as exploited in the wild in August through October 2023.
Istio is an open platform to connect, manage, and secure microservices. In versions on the 1.15.x branch prior to 1.15.3, a user can impersonate any workload identity within the service mesh if they have localhost access to the Istiod control plane. Version 1.15.3 contains a patch for this issue. There are no known workarounds.