Security Bulletin
Summary
IBM Cloud Kubernetes Service is affected by a security vulnerability in the Kubernetes API server that exposes it to a denial of service attack via malicious YAML or JSON payloads (CVE-2019-11253)
Vulnerability Details
Description: The Kubernetes API server is vulnerable to a denial of service, caused by a billion laughs attack, caused by an error when parsing YAML manifests. A remote attacker could exploit this vulnerability to cause a denial of service condition.
CVSS Base Score: 7.5
CVSS Temporal Score: https://exchange.xforce.ibmcloud.com/vulnerabilities/168618 for more information
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Affected Products and Versions
IBM Cloud Kubernetes Service 1.14.0-1.14.7
IBM Cloud Kubernetes Service 1.13.0-1.13.11
IBM Cloud Kubernetes Service 1.5-1.12
Remediation/Fixes
Updates for IBM Cloud Kubernetes Service clusters at versions 1.13 and 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:
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-update --cluster <cluster name or ID> --kube-version 1.##
Customers running IBM Cloud Kubernetes Service clusters at versions 1.11 or 1.12 must upgrade their affected clusters to version 1.13. Customers running IBM Cloud Kubernetes Service clusters at version 1.10 must upgrade first to version 1.12 and then to version 1.13. Please review the documentation before starting an upgrade since additional actions may be required.
Customers running IBM Cloud Kubernetes Service clusters at version 1.5, 1.7, 1.8 or 1.9 must create a new cluster and deploy their apps to the new cluster.
Note: IBM Cloud Kubernetes Service versions 1.5, 1.7, 1.8, 1.9, 1.10 and 1.11 are no longer supported, and version 1.12 is deprecated. See the IBM Cloud Kubernetes Service Version information and update actions documentation for more information about Kubernetes versions and version support policies.
Workarounds and Mitigations
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
Change History
DD MMM 2019: Original version published
*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.
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Document Information
Modified date:
25 October 2019
UID
ibm11098759