On January 26, 2021, details were made public about a security flaw that impacts many distributions of Linux, including Red Hat Enterprise Linux CoreOS, which is a component of Red Hat OpenShift Dedicated (OSD) and Azure Red Hat OpenShift (ARO). For information on this CVE, visit CVE-2021-3156. The security bulletin can be found here.

The intent of this blog is to notify our customers and the community of the actions Red Hat and the OpenShift SRE team have taken to analyze and protect OSD and ARO.

Impact to Red Hat OpenShift Dedicated and Azure Red Hat OpenShift

  • To use the flawed sudo on an OSD or ARO cluster, a user would need access to the underlying nodes via a highly-privileged container, for example using the `oc debug` facility.
  • This highly-privileged access is available only to users who already have cluster-admin access to their clusters. There is no higher level of access that can be obtained by exploiting this flaw.
  • Therefore, while the CVE severity is rated as Important, the impact of this flaw for OSD and ARO customers is Low.
  • Because of the Low rating for OSD and ARO, Red Hat will not force emergency cluster upgrades to remediate this flaw.


  • When a patched OpenShift version is available, OSD and ARO customers should apply the upgrade per their normal policies and timelines. 


  • Prior to the public announcement, OpenShift SRE and Red Hat Product Security analyzed the flaw to determine its impact to OSD and ARO.
  • OpenShift SRE analyzed historic logs to determine if this flaw had previously been exploited. The analysis showed no evidence of exploitation.
  • On January 26, 2021, at approximately 18:00 (UTC), details about this flaw and its remediations were publicly announced.
  • The remediation will be available via the standard OSD/ARO upgrade process.

Any questions about the vulnerability should be directed to Red Hat Support.

At Red Hat, the safety and security of our customers’ systems and data is of utmost importance. Thank you for your continued trust and confidence in working with Red Hat.

-Red Hat OpenShift SRE Team