Security Bulletin
Summary
IBM Cloud Kubernetes Service is affected by a security vulnerability found in containerd that could allow containers using the same image to share environment variables (CVE-2021-21334).
Vulnerability Details
CVEID: CVE-2021-21334
In containerd (an industry-standard container runtime) before versions 1.3.10 and 1.4.4, containers launched through containerd’s CRI implementation (through Kubernetes, crictl, or any other pod/container client that uses the containerd CRI service) that share the same image may receive incorrect environment variables, including values that are defined for other containers. If the affected containers have different security contexts, this may allow sensitive information to be unintentionally shared. If you are not using containerd’s CRI implementation (through one of the mechanisms described above), you are not vulnerable to this issue. If you are not launching multiple containers or Kubernetes pods from the same image which have different environment variables, you are not vulnerable to this issue. If you are not launching multiple containers or Kubernetes pods from the same image in rapid succession, you have reduced likelihood of being vulnerable to this issue This vulnerability has been fixed in containerd 1.3.10 and containerd 1.4.4. Users should update to these versions.
CVSS Base Score: 7.5
CVSS Temporal Score: https://exchange.xforce.ibmcloud.com/vulnerabilities/198079 for more information
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)
Affected Products and Versions
IBM Cloud Kubernetes Service 1.20.0-1.20.4_1531
IBM Cloud Kubernetes Service 1.19.0-1.19.8_1538
IBM Cloud Kubernetes Service 1.18.0-1.18.16_1544
IBM Cloud Kubernetes Service 1.17.0-1.17.17_1555
IBM Cloud Kubernetes Service 1.5-1.16
Remediation/Fixes
Updates for IBM Cloud Kubernetes Service cluster worker nodes at versions 1.17 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:
1.20.4_1532
1.19.8_1539
1.18.16_1545
1.17.17_1556
Customers running IBM Cloud Kubernetes Service clusters at version 1.16 must upgrade to version 1.17. Please review the documentation before starting an upgrade since additional actions may be required.
Customers running IBM Cloud Kubernetes Service clusters at version 1.15 or earlier must create a new cluster and deploy their apps to the new cluster.
IBM Cloud Kubernetes Service versions 1.16 and earlier are no longer supported, and version 1.17 is deprecated. See the IBM Cloud Kubernetes Service version information and update actions documentation for more information about Kubernetes versions and version support policies.
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References
*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:
22 March 2021
UID
ibm16433475