Envoy is an open source edge and service proxy, designed for cloud-native applications. When a cluster is deleted via Cluster Discovery Service (CDS) all idle connections established to endpoints in that cluster are disconnected. A recursion was introduced in the procedure of disconnecting idle connections that can lead to stack exhaustion and abnormal process termination when a cluster has a large number of idle connections. This infinite recursion causes Envoy to crash. Users are advised to upgrade.
https://github.com/envoyproxy/envoy/security/advisories/GHSA-9vp2-4cp7-vvxf
https://github.com/envoyproxy/envoy/commit/4b6dd3b53cd5c6d4d4df378a2fc62c1707522b31