Ingress nginx annotation injection causes arbitrary command execution.

### Issue Details

A security issue was identified in [ingress-nginx](https://github.com/kubernetes/ingress-nginx) where the nginx.ingress.kubernetes.io/configuration-snippet annotation on an Ingress object (in the `networking.k8s.io` or `extensions` API group) can be used to inject arbitrary commands, and obtain the credentials of the ingress-nginx controller. In the default configuration, that credential has access to all secrets in the cluster.

This issue has been rated **High** ([CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L](https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L)), and assigned **CVE-2023-5043**.

### Affected Components and Configurations
This bug affects ingress-nginx. If you do not have ingress-nginx installed on your cluster, you are not affected. You can check this by running `kubectl get po -n ingress-nginx`.

If you are running the “chrooted” ingress-nginx controller introduced in v1.2.0 (gcr.io/k8s-staging-ingress-nginx/controller-chroot), command execution is possible but credential extraction is not, so the High severity does not apply.

Multi-tenant environments where non-admin users have permissions to create Ingress objects are most affected by this issue.

#### Affected Versions

- <v1.9.0

#### Versions allowing mitigation

- v1.9.0

### Mitigation
Ingress Administrators should set the --enable-annotation-validation flag to enforce restrictions on the contents of ingress-nginx annotation fields.

### Detection
If you find evidence that this vulnerability has been exploited, please contact [security@kubernetes.io](mailto:security@kubernetes.io)

### Additional Details
See ingress-nginx Issue[ #10571](https://github.com/kubernetes/ingress-nginx/issues/10571) for more details.

### Acknowledgements
This vulnerability was reported by suanve

Thank You,
CJ Cullen on behalf of the Kubernetes Security Response Committee
CVE-2023-5043: Ingress nginx annotation injection causes arbitrary command execution
This is a GitHub Issue
repo:ingress-nginx
owner:kubernetes
Title : CVE-2023-5043: Ingress nginx annotation injection causes arbitrary command execution
Issue date:

--- start body ---
### Issue Details

A security issue was identified in [ingress-nginx](https://github.com/kubernetes/ingress-nginx) where the nginx.ingress.kubernetes.io/configuration-snippet annotation on an Ingress object (in the `networking.k8s.io` or `extensions` API group) can be used to inject arbitrary commands, and obtain the credentials of the ingress-nginx controller. In the default configuration, that credential has access to all secrets in the cluster.

This issue has been rated **High** ([CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L](https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L)), and assigned **CVE-2023-5043**.

### Affected Components and Configurations
This bug affects ingress-nginx. If you do not have ingress-nginx installed on your cluster, you are not affected. You can check this by running `kubectl get po -n ingress-nginx`.

If you are running the “chrooted” ingress-nginx controller introduced in v1.2.0 (gcr.io/k8s-staging-ingress-nginx/controller-chroot), command execution is possible but credential extraction is not, so the High severity does not apply.

Multi-tenant environments where non-admin users have permissions to create Ingress objects are most affected by this issue.

#### Affected Versions

- <v1.9.0

#### Versions allowing mitigation

- v1.9.0

### Mitigation
Ingress Administrators should set the --enable-annotation-validation flag to enforce restrictions on the contents of ingress-nginx annotation fields.

### Detection
If you find evidence that this vulnerability has been exploited, please contact [security@kubernetes.io](mailto:security@kubernetes.io)

### Additional Details
See ingress-nginx Issue[ #10571](https://github.com/kubernetes/ingress-nginx/issues/10571) for more details.

### Acknowledgements
This vulnerability was reported by suanve

Thank You,
CJ Cullen on behalf of the Kubernetes Security Response Committee
--- end body ---

A security vulnerability (CVE-2023-5043) in ingress-nginx allows for arbitrary command execution through the nginx.ingress.kubernetes.io/configuration-snippet annotation. This can lead to credential extraction of the ingress-nginx controller, which has access to all secrets in the cluster. The issue is rated High severity and affects versions prior to v1.9.0, particularly in multi-tenant environments where non-admin users can create Ingress objects.