KubeVirt is a virtual machine management add-on for Kubernetes. Versions 1.5.3 and below, and 1.6.0 contained a flawed implementation of the Kubernetes aggregation layer's authentication flow which could enable bypass of RBAC controls. It was discovered that the virt-api component fails to correctly authenticate the client when receiving API requests over mTLS. In particular, it fails to validate the CN (Common Name) field in the received client TLS certificates against the set of allowed values defined in the extension-apiserver-authentication configmap. Failre to validate certain fields in the client TLS certificate may allow an attacker to bypass existing RBAC controls by directly communicating with the aggregated API server, impersonating the Kubernetes API server and its aggregator component. This issue is fixed in versions 1.5.3 and 1.6.1.
https://github.com/kubevirt/kubevirt/security/advisories/GHSA-38jw-g2qx-4286
https://github.com/kubevirt/kubevirt/commit/b9773bc588e6e18ece896a2dad5336ef7a653074
https://github.com/kubevirt/kubevirt/commit/af2f08a9a186eccc650f87c30ab3e07b669e8b5b
https://github.com/kubevirt/kubevirt/commit/231dc69723f331dc02f65a31ab4c3d6869f40d6a