> For the complete documentation index, see [llms.txt](https://cortex-docs.paloaltonetworks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cortex-docs.paloaltonetworks.com/appsec-rules/iac-security/networking/appsec-k8s-4.md).

# Containers wishing to share host network namespace admitted misconfiguration detected in code

## Rule Details

|                        |                                                        |
| ---------------------- | ------------------------------------------------------ |
| Cortex AppSec Rule ID  | APPSEC\_K8S\_4                                         |
| Category - Subcategory | Kubernetes - Access Control                            |
| Provider               | OTHER                                                  |
| Severity               | MEDIUM                                                 |
| Framework              | Helm, Kubernetes, Kustomize, Terraform, Terraform Plan |

## Impact

In a Kubernetes cluster, every pod gets its own IP address. Pods can be treated much like VMs or physical hosts from the perspectives of port allocation, naming, service discovery, load balancing, application configuration, and migration. Sharing the host network namespace breaks the isolation between container images and can make the host visible to other containers in the pod. In some cases, pods in the host network of a node can communicate with all pods on all nodes without using network address translation (NAT).

## How to Fix

*Resource:* PodSecurityPolicy

* *Arguments:* hostNetwork (Optional) When set to false, Pods are unable to use their host's network namespace.

To use a **PodSecurityPolicy** resource, the requesting user or target pod's service account must be authorized to use the policy. The preferred method is to grant access to the service account.

In the following example we use **RBAC**, a standard Kubernetes authorization mode.

A *Role* or *ClusterRole* needs to grant access to *use* the desired policies.

*Kind*: ClusterRole

The **ClusterRole** is then bound to the authorized service(s):

## *Kind*: ClusterRoleBinding \[source,go]

apiVersion: policy/v1beta1 kind: PodSecurityPolicy metadata: name: spec:

* hostNetwork: false

***

apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRole metadata: name: rules:

* apiGroups: \['policy'] resources: \['podsecuritypolicies'] verbs: \['use'] resourceNames:
*

***

apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: roleRef: kind: ClusterRole name: apiGroup: rbac.authorization.k8s.io subjects:

* kind: ServiceAccount name: namespace:

***


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