Security Bulletin: IBM Cloud Kubernetes Service is affected by a containerd security vulnerability (CVE-2021-32760)

Summary

IBM Cloud Kubernetes Service is affected by a security vulnerability found in containerd that could result in file permission changes for existing files in the host’s filesystem (CVE-2021-32760)

Vulnerability Details

CVEID: CVE-2021-32760
Description: Containerd could allow a remote attacker to gain elevated privileges on the system, caused by improper file permissions. By pulling and extracting a specially-crafted container image, an attacker could exploit this vulnerability to perform Unix file permission changes for existing files in the host’s filesystem.
CVSS Base Score: 9.8
CVSS Temporal Score: <https://exchange.xforce.ibmcloud.com/vulnerabilities/205942&gt; for more information
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)

Affected Products and Versions

IBM Cloud Kubernetes Service 1.21.0-1.21.2_1524
IBM Cloud Kubernetes Service 1.20.0-1.20.8_1546
IBM Cloud Kubernetes Service 1.19.0-1.19.12_1553
IBM Cloud Kubernetes Service 1.5-1.18

Remediation/Fixes

Updates for IBM Cloud Kubernetes Service cluster worker nodes at versions 1.19 or later are available that fix this vulnerability. Customers must update worker nodes created before the fix was available to address the vulnerability. See updating worker nodes for details on updating worker nodes. To verify your cluster worker nodes have been updated, use the following IBM Cloud CLI command to confirm the currently running versions:

ibmcloud ks workers --cluster <cluster name or ID>

If the versions are at one of the following patch levels or later, the cluster worker nodes have the fix:

1.21.3_1526
1.20.9_1548
1.19.13_1555

Customers running IBM Cloud Kubernetes Service clusters at version 1.17 or 1.18 must upgrade to version 1.19. Please review the documentation before starting an upgrade since additional actions may be required.

Customers running IBM Cloud Kubernetes Service clusters at version 1.16 or earlier must create a new cluster and deploy their apps to the new cluster.

IBM Cloud Kubernetes Service versions 1.17 and earlier are no longer supported, and version 1.18 is deprecated. 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

Containerd Advisory: Archive package allows chmod of file outside of unpack target directory

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.

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