Security Bulletin: Red Hat OpenShift on IBM Cloud is affected by a Kubernetes controller manager security vulnerability (CVE-2020-8555)

Summary

Red Hat OpenShift on IBM Cloud is affected by a security vulnerability in the Kubernetes controller manager that could leak data to authorized users (CVE-2020-8555)

Vulnerability Details

CVEID: CVE-2020-8555
Description: Kubernetes is vulnerable to server-side request forgery, caused by a flaw in the kube-controller-manager. By using a specially-crafted argument, a remote authenticated attacker could exploit this vulnerability to conduct SSRF attack to leak up to 500 bytes of arbitrary information from unprotected endpoints.
CVSS Base Score: 3.5
CVSS Temporal Score: <https://exchange.xforce.ibmcloud.com/vulnerabilities/182744&gt; for more information
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N)

Affected Products and Versions

Red Hat OpenShift on IBM Cloud 4.3.0-4.3.27
Red Hat OpenShift on IBM Cloud 3.11.0-3.11.231

Remediation/Fixes

Updates for Red Hat OpenShift on IBM Cloud clusters at versions 3.11 or 4.3 are available that fix this vulnerability. Red Hat OpenShift on IBM Cloud 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 oc clusters

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

4.3.28
3.11.232

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 X.Y with the target version.

ibmcloud oc cluster master update --cluster <cluster name or ID> --version X.Y_openshift

Workarounds and Mitigations

Red Hat OpenShift on IBM Cloud partially mitigates this vulnerability via endpoint protections for cluster masters. Customers can further mitigate this vulnerability by Configuring security context contraints and restricting RBAC in order to limit access for authorized users as is detailed in the Kubernetes security advisory CVE-2020-8555: Half-Blind SSRF in kube-controller-manager.

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

Kubernetes Security Announcement for CVE-2020-8555

Related Information

IBM Secure Engineering Web Portal
IBM Product Security Incident Response Blog

*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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