In go.etcd.io/etcd/client/pkg/v3 before 3.5.33, 3.6.14, and 3.7.1, TLS handshakes on listeners created by NewTLSListener do not enforce a handshake deadline. An unauthenticated network attacker who connects to an etcd TLS listener without sending a ClientHello causes a goroutine and a tracking map entry to block indefinitely. Opening many such connections exhausts memory, leading to a denial of service.