Kubernetes vulnerabilities

A security issue was discovered in ingress-nginx where the `nginx.ingress.kubernetes.io/auth-proxy-set-headers` Ingress annotation can be used to inject configuration into nginx. This can lead to arbitrary code execution in the context of the ingress-nginx controller, and disclosure of Secrets accessible to the controller. (Note that in the default installation, the controller can access all Secrets cluster-wide.)

A vulnerability exists in the NodeRestriction admission controller where nodes can bypass dynamic resource allocation authorization checks. When the DynamicResourceAllocation feature gate is enabled, the controller properly validates resource claim statuses during pod status updates but fails to perform equivalent validation during pod creation. This allows a compromised node to create mirror pods that access unauthorized dynamic resources, potentially leading to privilege escalation.

A security issue was discovered in ingress-nginx https://github.com/kubernetes/ingress-nginx where the `auth-url` Ingress annotation can be used to inject configuration into nginx. This can lead to arbitrary code execution in the context of the ingress-nginx controller, and disclosure of Secrets accessible to the controller. (Note that in the default installation, the controller can access all Secrets cluster-wide.)

A security issue was discovered in ingress-nginx https://github.com/kubernetes/ingress-nginx where attacker-provided data are included in a filename by the ingress-nginx Admission Controller feature, resulting in directory traversal within the container. This could result in denial of service, or when combined with other vulnerabilities, limited disclosure of Secret objects from the cluster.

A security issue was discovered in Kubernetes where under certain conditions, an unauthenticated attacker with access to the pod network can achieve arbitrary code execution in the context of the ingress-nginx controller. This can lead to disclosure of Secrets accessible to the controller. (Note that in the default installation, the controller can access all Secrets cluster-wide.)

A security issue was discovered in ingress-nginx https://github.com/kubernetes/ingress-nginx where the `mirror-target` and `mirror-host` Ingress annotations can be used to inject arbitrary configuration into nginx. This can lead to arbitrary code execution in the context of the ingress-nginx controller, and disclosure of Secrets accessible to the controller. (Note that in the default installation, the controller can access all Secrets cluster-wide.)

A security issue was discovered in ingress-nginx https://github.com/kubernetes/ingress-nginx where the `auth-tls-match-cn` Ingress annotation can be used to inject configuration into nginx. This can lead to arbitrary code execution in the context of the ingress-nginx controller, and disclosure of Secrets accessible to the controller. (Note that in the default installation, the controller can access all Secrets cluster-wide.)

This CVE only affects Kubernetes clusters that utilize the in-tree gitRepo volume to clone git repositories from other pods within the same node. Since the in-tree gitRepo volume feature has been deprecated and will not receive security updates upstream, any cluster still using this feature remains vulnerable.

As mitigations to a report from 2019 and CVE-2020-8555, Kubernetes attempts to prevent proxied connections from accessing link-local or localhost networks when making user-driven connections to Services, Pods, Nodes, or StorageClass service providers. As part of this mitigation Kubernetes does a DNS name resolution check and validates that response IPs are not in the link-local (169.254.0.0/16) or localhost (127.0.0.0/8) range. Kubernetes then performs a second DNS resolution without validation for the actual connection. If a non-standard DNS server returns different non-cached responses, a user may be able to bypass the proxy IP restriction and access private networks on the control plane.

kubectl does not neutralize escape, meta or control sequences contained in the raw data it outputs to a terminal. This includes but is not limited to the unstructured string fields in objects such as Events.

A security issue was discovered with Kubernetes that could enable users to send network traffic to locations they would otherwise not have access to via a confused deputy attack.

A security issue was discovered in Kubernetes where actors that control the responses of MutatingWebhookConfiguration or ValidatingWebhookConfiguration requests are able to redirect kube-apiserver requests to private networks of the apiserver. If that user can view kube-apiserver logs when the log level is set to 10, they can view the redirected responses and headers in the logs.

Kubernetes API server in all versions allow an attacker who is able to create a ClusterIP service and set the spec.externalIPs field, to intercept traffic to that IP address. Additionally, an attacker who is able to patch the status (which is considered a privileged operation and should not typically be granted to users) of a LoadBalancer service can set the status.loadBalancer.ingress.ip to similar effect.

Improper input validation in the Kubernetes API server in versions v1.0-1.12 and versions prior to v1.13.12, v1.14.8, v1.15.5, and v1.16.2 allows authorized users to send malicious YAML or JSON payloads, causing the API server to consume excessive CPU or memory, potentially crashing and becoming unavailable. Prior to v1.14.0, default RBAC policy authorized anonymous users to submit requests that could trigger this vulnerability. Clusters upgraded from a version prior to v1.14.0 keep the more permissive policy by default for backwards compatibility.

Default access permissions for Persistent Volumes (PVs) created by the Kubernetes Azure cloud provider in versions 1.6.0 to 1.6.5 are set to "container" which exposes a URI that can be accessed without authentication on the public internet. Access to the URI string requires privileged access to the Kubernetes cluster or authenticated access to the Azure portal.

Kubernetes in OpenShift3 allows remote authenticated users to use the private images of other users should they know the name of said image.

Kubernetes version 1.5.0-1.5.4 is vulnerable to a privilege escalation in the PodSecurityPolicy admission plugin resulting in the ability to make use of any existing PodSecurityPolicy object.

Openshift allows remote attackers to gain privileges by updating a build configuration that was created with an allowed type to a type that is not allowed.

The API server in Kubernetes does not properly check admission control, which allows remote authenticated users to access additional resources via a crafted patched object.