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TI-2021-03533 Aliases CVE-2021-20238

Improper authentication in openshift/machine-config-operator

Priority LOW 19CWE-287Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
High
Impact type
Security bypass
Confidentiality · integrity · availability
Low · None · None
Fix status
Will not fix Red Hat: no fix planned

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-287.

Summary

It was found in OpenShift Container Platform 4 that ignition config, served by the Machine Config Server, can be accessed externally from clusters without authentication. The MCS endpoint (port 22623) provides ignition configuration used for bootstrapping Nodes and can include some sensitive data, e.g. registry pull secrets. There are two scenarios where this data can be accessed. The first is on Baremetal, OpenStack, Ovirt, Vsphere and KubeVirt deployments which do not have a separate internal API endpoint and allow access from outside the cluster to port 22623 from the standard OpenShift API Virtual IP address. The second is on cloud deployments when using unsupported network plugins, which do not create iptables rules that prevent to port 22623. In this scenario, the ignition config is exposed to all pods within the cluster and cannot be accessed externally.

Why it matters now

EPSS 0.00765 55th percentileScored 2026-11-07
Fix Will not fix Red Hat: no fix planned

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
—openshift/machine-config-operatoraffecting versions up to, including ose-machine-config-operator-container-v4.9.0—No fix listedCNA
  • openshift/machine-config-operator Vendor— Affected affecting versions up to, including ose-machine-config-operator-container-v4.9.0 Fixed in — No fix listed CNA

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:*4.0VulnerableRed Hat
cpe:2.3:a:redhat:openshift_machine-config-operator:*:*:*:*:*:*:*:*up to 4.9.0VulnerableRed Hat
  • cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:* Versions 4.0 Vulnerable ·Red Hat
  • cpe:2.3:a:redhat:openshift_machine-config-operator:*:*:*:*:*:*:*:* Versions up to 4.9.0 Vulnerable ·Red Hat

Remediation

No fixed version listed by the sources yet.

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat OpenShift Container Platform 4AffectedNo fix planned: Will not fix
Not affected: 1 product
  • Red Hat OpenShift Container Platform 3.11

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-20238

References

Advisory 1

  • TI-2019-15875 Protection mechanism failure in Jenkins Pipeline: Groovy Plugin KEVCVSS 3.1CRITICAL 9.9
  • TI-2019-15874 Protection mechanism failure in Jenkins Script Security Plugin KEVCVSS 3.1CRITICAL 9.9
  • TI-2019-05363 Code injection in Elastic Kibana KEVCVSS 3.1CRITICAL 10.0
  • TI-2018-16080 A code execution vulnerability exists in the Stapler web framework used by Jenkins 2.153… KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-34021 Linux kernel skb coalescing drops shared-frag marker KEVCVSS 3.1HIGH 7.8
  • TI-2026-23989 crypto: algif_aead - Revert to operating out-of-place KEVCVSS 3.1HIGH 7.8
See all 340 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences