A security issue was discovered in Kubernetes where actors that control the responses of MutatingWebhookConfiguration or ValidatingWebhookConfiguration requests are able to redirect kube-apiserver requests to private networks of the apiserver. If that user can view kube-apiserver logs when the log level is set to 10, they can view the redirected responses and headers in the logs.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-8561
• kubernetes/kubernetes#104720
• https://groups.google.com/g/kubernetes-security-announce/c/RV2IhwcrQsY
• https://security.netapp.com/advisory/ntap-20211014-0002/