Security Bulletin: IBM Cloud Kubernetes Service is affected by a containerd security vulnerability (CVE-2021-30465)

Summary

IBM Cloud Kubernetes Service is affected by a security vulnerability found in containerd that could allow certain container configuration requests to actually result in the host filesystem being bind-mounted into the container (allowing for a container escape) (CVE-2021-30465).

Vulnerability Details

CVEID: CVE-2021-30465
Description: Open Container Initiative runc could allow a remote authenticated attacker to bypass security restrictions, caused by a symlink exchange attack. By sending a specially-crafted request, an attacker could exploit this vulnerability to allow host filesystem being bind-mounted into the container.
CVSS Base Score: 7.6
CVSS Temporal Score: <https://exchange.xforce.ibmcloud.com/vulnerabilities/202132&gt; for more information
CVSS Vector: (CVSS:3.0/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N)

Affected Products and Versions

IBM Cloud Kubernetes Service 1.20.0-1.20.6_1539
IBM Cloud Kubernetes Service 1.19.0-1.19.10_1546
IBM Cloud Kubernetes Service 1.5-1.18

Remediation/Fixes

Updates for IBM Cloud Kubernetes Service cluster worker nodes at version 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:

1.20.7_1541

1.19.11_1548

Customers running IBM Cloud Kubernetes Service clusters at version 1.16, 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 1.15 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

Complete CVSS v3 Guide
On-line Calculator v3

Off

Security advisory for runc

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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