A security issue was discovered in Kubernetes that could allow Windows workloads to run as ContainerAdministrator even when those workloads set the runAsNonRoot option to true.

This issue has been rated low and assigned CVE-2021-25749

Am I vulnerable?

All Kubernetes clusters with following versions, running Windows workloads with runAsNonRoot are impacted

Affected Versions

• kubelet v1.20 - v1.21
• kubelet v1.22.0 - v1.22.13
• kubelet v1.23.0 - v1.23.10
• kubelet v1.24.0 - v1.24.4

How do I mitigate this vulnerability?

There are no known mitigations to this vulnerability.

Fixed Versions

• kubelet v1.22.14
• kubelet v1.23.11
• kubelet v1.24.5
• kubelet v1.25.0

To upgrade, refer to this documentation For core Kubernetes: https://kubernetes.io/docs/tasks/administer-cluster/cluster-upgrade/

Detection

Kubernetes Audit logs may indicate if the user name was misspelled to bypass the restriction placed on which user is a pod allowed to run as.

If you find evidence that this vulnerability has been exploited, please contact security@kubernetes.io

Additional Details

See the GitHub issue for more details: #112192

Acknowledgements

This vulnerability was reported and fixed by Mark Rosetti (@marosset)