[ANNOUNCE] Security regression in Kubernetes kubelet v1.13.6 and v1.14.2 only - CVE-2019-11245

159 views

Skip to first unread message

Brandon Philips

unread,

May 30, 2019, 5:57:44 PM5/30/19

to Kubernetes developer/contributor discussion, kubernetes-sec...@googlegroups.com, kubernetes-security-discuss, oss-se...@lists.openwall.com, kubernetes-distr...@googlegroups.com

Hello Kubernetes Community-

A security-related issue was discovered in kubelet versions v1.13.6 and v1.14.2. The issue is medium severity and can be mitigated with a pod spec configuration change OR by **downgrading** kubelets to v1.13.5 or v1.14.1.

**Vulnerability Details**

When a container runs for the first time on a node, it correctly respects the UID set by the container image (e.g. USER in a Dockerfile). However, on the second run, the container will run as UID 0 (aka root) which can be an undesired escalated privilege.

Pods that specify an explicit runAsUser are unaffected and continue to work properly.

PodSecurityPolicies that force a runAsUser setting are also unaffected and continue to work properly.

Pods that specify mustRunAsNonRoot:true will refuse to start the container as uid 0, which can affect availability.

This issue is filed as CVE-2019-11245. See https://github.com/kubernetes/kubernetes/issues/78308 for more details.

**Am I vulnerable?**

Run this to print out all nodes and their kubelet version:

kubectl get nodes -o=jsonpath='{range .items[*]}{.status.nodeInfo.machineID}{"\t"}{.status.nodeInfo.kubeletVersion}{"\n"}{end}'

If the output lists Kubelet versions listed below you are running a vulnerable version:

v1.13.6
v1.14.2

**How do I mitigate the vulnerability?**

There are two potential mitigations to this issue:

Downgrade to kubelet v1.13.5 or v1.14.1 as instructed by your Kubernetes distribution.
Set RunAsUser on all pods in the cluster that should not run as root. This is a Security Context feature; the docs are at https://kubernetes.io/docs/tasks/configure-pod-container/security-context/#set-the-security-context-for-a-pod

**How do I upgrade?**

An upgrade addressing this issue is not yet available. But, will appear in v1.13.7 and v1.14.3 ASAP and will be announced here.

**Thank you**

Thank you to the many reporters, and Tim Pepper as release manager for the coordination in making this announcement.

Thank You,

Brandon on behalf of the Kubernetes Product Security Committee

Tim Pepper

unread,

Jun 7, 2019, 7:32:00 PM6/7/19

to Brandon Philips, Kubernetes developer/contributor discussion, kubernetes-sec...@googlegroups.com, kubernetes-security-discuss, oss-se...@lists.openwall.com, kubernetes-distr...@googlegroups.com

Just in case anybody missed it explicitly…v1.13.7 and v1.14.3 were released yesterday, including the change for this CVE.

Tim Pepper

Orchestration & Containers Lead

VMware Open Source Technology Center

--
You received this message because you are subscribed to the Google Groups "Kubernetes developer/contributor discussion" group.
To unsubscribe from this group and stop receiving emails from it, send an email to kubernetes-de...@googlegroups.com.
To post to this group, send email to kuberne...@googlegroups.com.
Visit this group at https://groups.google.com/group/kubernetes-dev.
To view this discussion on the web visit https://groups.google.com/d/msgid/kubernetes-dev/CAHHNuYcXG6rqgA%2By3efW8yb5Kbd9CgJq_MfgKz8cUgp4AqbXRg%40mail.gmail.com.
For more options, visit https://groups.google.com/d/optout.