Uncontrolled Resource Consumption
Istio is an open platform to connect, manage, and secure microservices. In affected versions the Istio control plane, istiod, is vulnerable to a request processing error, allowing a malicious attacker that sends a specially crafted message which results in the control plane crashing when the validating webhook for a cluster is exposed publicly. This endpoint is served over TLS port 15017, but does not require any authentication from the attacker. For simple installations, Istiod is typically only reachable from within the cluster, limiting the blast radius. However, for some deployments, especially [external istiod](https://istio.io/latest/docs/setup/install/external-controlplane/) topologies, this port is exposed over the public internet. This issue has been patched in versions 1.11.8, 1.12.5 and 1.13.2. Users are advised to upgrade. Users unable to upgrade should disable access to a validating webhook that is exposed to the public internet or restrict the set of IP addresses that can query it to a set of known, trusted entities.
CWE-400 - Uncontrolled resource consumption
An uncontrolled resource allocation attack (also known as resource exhaustion attack) triggers unauthorized overconsumption of the limited resources in an application, such as memory, file system storage, database connection pool entries, and CPU. This may lead to denial of service for valid users and degradation of the application's functionality as well as that of the host operating system.