CVE-2020-8562

As mitigations to a report from 2019 and CVE-2020-8555, Kubernetes attempts
to prevent proxied connections from accessing link-local or localhost
networks when making user-driven connections to Services, Pods, Nodes, or
StorageClass service providers. As part of this mitigation Kubernetes does
a DNS name resolution check and validates that response IPs are not in the
link-local (169.254.0.0/16) or localhost (127.0.0.0/8) range. Kubernetes
then performs a second DNS resolution without validation for the actual
connection. If a non-standard DNS server returns different non-cached
responses, a user may be able to bypass the proxy IP restriction and access
private networks on the control plane.

Notes