CVE-2023-22651

First published: Mon Apr 24 2023(Updated: )

### Impact A failure in the update logic of Rancher's admission Webhook may lead to the misconfiguration of the Webhook. This component enforces validation rules and security checks before resources are admitted into the Kubernetes cluster. When the Webhook is operating in a degraded state, it no longer validates any resources, which may result in severe privilege escalations and data corruption. The issue only affects users that upgrade from `2.6.x` or `2.7.x` to `2.7.2`. Users that did a fresh install of 2.7.2 (and did not follow an upgrade path) are not affected. The command below can be executed on the `local` cluster to determine whether the cluster is affected by this issue: ```sh $ kubectl get validatingwebhookconfigurations.admissionregistration.k8s.io rancher.cattle.io NAME WEBHOOKS AGE rancher.cattle.io 0 19h ``` If the resulting webhook quantity is `0`, the Rancher instance is affected. ### Patches Patched versions include release `2.7.3` and later versions. ### Workarounds If you are affected and cannot update to a patched Rancher version, the recommended workaround is to manually reconfigure the Webhook with the script below. Please note that the script must be run from inside the `local` cluster or with a kubeconfig pointing to the `local` cluster which has admin permissions. ```yaml #!/bin/bash set -euo pipefail function prereqs() { if ! [ -x "$(command -v kubectl)" ]; then echo "error: kubectl is not installed." >&2 exit 1 fi if [[ -z "$(kubectl config view -o jsonpath='{.clusters[].cluster.server}')" ]]; then echo "error: No kubernetes cluster found on kubeconfig." >&2 exit 1 fi } function restart_deployment(){ kubectl rollout restart deployment rancher-webhook -n cattle-system kubectl rollout status deployment rancher-webhook -n cattle-system --timeout=30s } function workaround() { echo "Cluster: $(kubectl config view -o jsonpath='{.clusters[].cluster.server}')" if ! kubectl get validatingwebhookconfigurations.admissionregistration.k8s.io rancher.cattle.io > /dev/null 2>&1; then echo "webhook rancher.cattle.io not found, restarting deployment:" restart_deployment echo "waiting for webhook configuration" sleep 15s fi local -i webhooks webhooks="$(kubectl get validatingwebhookconfigurations.admissionregistration.k8s.io rancher.cattle.io --no-headers | awk '{ print $2 }')" if [ "${webhooks}" == "0" ]; then echo "Webhook misconfiguration status: Cluster is affected by CVE-2023-22651" echo "Running workaround:" kubectl delete validatingwebhookconfiguration rancher.cattle.io restart_deployment ret=$? if [ $ret -eq 0 ]; then echo "Webhook restored, CVE-2023-22651 is fixed" else echo "error trying to restart deployment. try again in a few seconds." fi else echo "Webhook misconfiguration status: not present (skipping)" fi echo "Done" } function main() { prereqs workaround } main ``` ### References - https://github.com/rancher/webhook/pull/216/commits/a4a498613b43a3ee93c5ab06742a3bc8adace45d ### For more information If you have any questions or comments about this advisory: - Reach out to the [SUSE Rancher Security team](https://github.com/rancher/rancher/security/policy) for security related inquiries. - Open an issue in the [Rancher](https://github.com/rancher/rancher/issues/new/choose) repository. - Verify our [support matrix](https://www.suse.com/suse-rancher/support-matrix/all-supported-versions/) and [product support lifecycle](https://www.suse.com/lifecycle/).

Credit: meissner@suse.de meissner@suse.de

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