### CVE-2021-25735: Validating Admission Webhook does not observe some previous fields

A security issue was discovered in kube-apiserver that could allow node
updates to bypass a Validating Admission Webhook. You are only affected
by this vulnerability if you run a Validating Admission Webhook for Nodes
that denies admission based at least partially on the old state of the
Node object.

kind: ValidatingWebhookConfiguration
metadata:
  labels:
    app: istiod
    istio: istiod
    istio.io/rev: default
    release: istio
  name: istio-validator-istio-system
webhooks:
- admissionReviewVersions:
  - v1beta1
  - v1
  clientConfig:
    service:
      name: istiod
      namespace: istio-system
      path: /validate
  failurePolicy: Ignore

        "properties": {
          "gmsaCredentialSpec": {
            "description": "GMSACredentialSpec is where the GMSA admission webhook (https://github.com/kubernetes-sigs/windows-gmsa) inlines the contents of the GMSA credential spec named by the GMSACredentialSpecName field.",
            "type": "string"
          },
          "gmsaCredentialSpecName": {