Security Bulletin
Summary
IBM Cloud Kubernetes Service is affected by security vulnerabilities in the Kubernetes API server that exposes it to denial of service attacks (CVE-2019-11254 and CVE-2020-8552)
Vulnerability Details
DESCRIPTION: Kubernetes is vulnerable to a denial of service, caused by a flaw in kube-apiserver. By sending a specially-crafted request using YAML payloads, a remote authenticated attacker could exploit this vulnerability to consume excessive CPU cycles.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/178935 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
CVEID: CVE-2020-8552
DESCRIPTION: Kubernetes kube-apiserver is vulnerable to a denial of service, caused by improper input validation. By sending a specially-crafted resource request, a remote attacker could exploit this vulnerability to cause a denial of service condition.
CVSS Base Score: 5.3
CVSS Temporal Score: https://exchange.xforce.ibmcloud.com/vulnerabilities/178254 for the current score.CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
Affected Products and Versions
IBM Cloud Kubernetes Service 1.16.0-1.16.6
IBM Cloud Kubernetes Service 1.15.0-1.15.9
IBM Cloud Kubernetes Service 1.5-1.14
Remediation/Fixes
Updates for IBM Cloud Kubernetes Service clusters at versions 1.15 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 master update --cluster <cluster name or ID> --version 1.##
Customers running IBM Cloud Kubernetes Service clusters at version 1.13 must upgrade first to version 1.14 and then to version 1.15. Please review the documentation before starting an upgrade since additional actions may be required.
Customers running IBM Cloud Kubernetes Service clusters at version 1.12 or earlier must create a new cluster and deploy their apps to the new cluster.
IBM Cloud Kubernetes Service versions 1.13 and earlier are no longer supported, and version 1.14 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
Customers running IBM Cloud Kubernetes Service clusters at versions 1.14 and later that have been upgraded from version 1.13 or earlier, are encouraged to follow the Kubernetes default RBAC policies for unauthenticated users post-upgrade migration action. Doing so helps mitigate which users are able to exploit a vulnerability like this. Clusters created at versions 1.14 or later already have these more secure defaults.
Monitor the security notifications on the IBM Cloud Status page to be advised of future security bulletins.
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:
30 April 2020
UID
ibm16203780