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 hostโs filesystem (CVE-2021-32760)
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 hostโs filesystem.
CVSS Base Score: 9.8
CVSS Temporal Score: <https://exchange.xforce.ibmcloud.com/vulnerabilities/205942> for more information
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
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
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 the security notifications on the IBM Cloud Status page to be advised of future security bulletins.
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Containerd Advisory: Archive package allows chmod of file outside of unpack target directory
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*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.
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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