Rogerio Bastos

**Name of the Vulnerable Software and Affected Versions** kube-apiserver (affected versions not specified) **Description** A security issue was discovered in kube-apiserver that could allow node updates to bypass a Validating Admission Webhook. Clusters are only affected by this vulnerability if they run a Validating Admission Webhook for Nodes that denies admission based at least partially on the old state of the Node object. The vulnerability can be exploited when an update action on node resources is performed and an admission controller is in place and configured to validate the action. The information that is provided to the admission controller could contain old configurations that overwrite values used for validation. Since the overwriting takes place before the validation, this could lead the admission controller to accept requests that should be blocked. **Recommendations** As a temporary workaround, consider disabling the Validating Admission Webhook for Nodes until a patch is available. Restrict access to the node update functionality to minimize the risk of exploitation. Avoid using the old state of the Node object in the admission controller's validation process until the issue is resolved. At the moment, there is no information about a newer version that contains a fix for this vulnerability.