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HistoryJul 13, 2023 - 1:54 p.m.

Security Bulletin: IBM Cloud Kubernetes Service is affected by a Kubernetes API server security vulnerability (CVE-2023-2728)

2023-07-1313:54:19
www.ibm.com
19
ibm cloud kubernetes service
kubernetes api server
vulnerability
cve-2023-2728
security fix
upgrade

6.5 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

HIGH

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N

0.001 Low

EPSS

Percentile

38.7%

Summary

IBM Cloud Kubernetes Service is affected by a security vulnerability in the Kubernetes API server that enables a user to bypass the mountable secrets policy enforced by the ServiceAccount admission plugin when using ephemeral containers with the kubernetes.io/enforce-mountable-secrets annotation (CVE-2023-2728).

Vulnerability Details

CVEID: CVE-2023-2728
Description: Kubernetes could allow a remote authenticated attacker to bypass security restrictions, caused by a flaw when the ServiceAccount admission plugin and the kubernetes.io/enforce-mountable-secrets annotation are used together with ephemeral containers. By sending a specially crafted request, an attacker could exploit this vulnerability to bypass the mountable secrets policy to launch containers.
CVSS Base Score: 6.5
CVSS Temporal Score: <https://exchange.xforce.ibmcloud.com/vulnerabilities/259627&gt; for more information
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N)

Affected Products and Versions

IBM Cloud Kubernetes Service 1.27.0-1.27.2
IBM Cloud Kubernetes Service 1.26.0-1.26.5
IBM Cloud Kubernetes Service 1.25.0-1.25.10
IBM Cloud Kubernetes Service 1.24.0-1.24.14
IBM Cloud Kubernetes Service 1.5-1.23

Remediation/Fixes

Updates for IBM Cloud Kubernetes Service clusters at version 1.24 or later are available that fix this vulnerability. IBM Cloud Kubernetes Service will attempt to automatically apply the fix to your cluster master. There is no need to update cluster worker nodes for this vulnerability.

To verify your clusters are no longer exposed to this vulnerability, use the following IBM Cloud CLI command to confirm your cluster master versions:

ibmcloud ks clusters

If your cluster masters are at one of the following versions or later, they are no longer exposed to this vulnerability:

1.27.3_1529
1.26.6_1541
1.25.11_1549
1.24.15_1573

If one or more of your clusters has not had its master automatically updated then use the following IBM Cloud CLI command to complete the cluster master update, replacing 1.## with the target version.

ibmcloud ks cluster master update --cluster &lt;cluster name or ID&gt; --version 1.##

Customers running IBM Cloud Kubernetes Service clusters at version 1.23 must upgrade to version 1.24. Please review the documentation before starting an upgrade since additional actions may be required.

Customers running IBM Cloud Kubernetes Service clusters at version 1.22 or earlier must create a new cluster and deploy their apps to the new cluster.

IBM Cloud Kubernetes Service versions 1.23 and earlier are no longer supported. See the IBM Cloud Kubernetes Service version information and update actions documentation for more information about Kubernetes versions and version support policies.

Monitor IBM Cloud Status for Future Security Bulletins

Monitor the security notifications on the IBM Cloud Status page to be advised of future security bulletins.

References

Complete CVSS v3 Guide
On-line Calculator v3

Off

CVE-2023-2727, CVE-2023-2728: Bypassing policies imposed by the ImagePolicyWebhook and bypassing mountable secrets policy imposed by the ServiceAccount admission plugin

Kubernetes: Admission Controllers Reference

IBM Cloud Kubernetes Service: Default service settings for Kubernetes components

Related Information

IBM Secure Engineering Web Portal
IBM Product Security Incident Response Blog

IBM Cloud Kubernetes Service does not enable the ImagePolicyWebhook admission controller so is not vulnerable to CVE-2023-2727.

*The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Security Bulletin.

Disclaimer

Review the IBM security bulletin disclaimer and definitions regarding your responsibilities for assessing potential impact of security vulnerabilities to your environment.

[{“Business Unit”:{“code”:“BU059”,“label”:“IBM Software w/o TPS”},“Product”:{“code”:“SSJTBP”,“label”:“IBM Cloud Kubernetes Service and Red Hat OpenShift on IBM Cloud”},“Component”:“–”,“Platform”:[{“code”:“PF025”,“label”:“Platform Independent”}],“Version”:“All Versions”,“Edition”:“”,“Line of Business”:{“code”:“LOB21”,“label”:“Public Cloud Platform”}}]

Product Synonym

IKS;

Affected configurations

Vulners
Node
ibmaspera_on_cloudMatchany

6.5 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

HIGH

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N

0.001 Low

EPSS

Percentile

38.7%