4.21 version change log
View information of version changes for major, minor, and patch updates that are available for your Red Hat® OpenShift® on IBM Cloud® clusters that run this version. Changes include updates to Red Hat OpenShift, Kubernetes, and IBM Cloud Provider components.
Overview
Unless otherwise noted in the change logs, the IBM Cloud provider version enables Red Hat OpenShift APIs and features that are at beta. Red Hat OpenShift alpha features are disabled and subject to change.
Check the Security Bulletins on IBM Cloud Status for security vulnerabilities that affect Red Hat OpenShift on IBM Cloud. You can filter the results to view only Kubernetes Service security bulletins that are relevant to Red Hat OpenShift on IBM Cloud. Change log entries that address other security vulnerabilities but don't include an IBM security bulletin are for vulnerabilities that are not known to affect Red Hat OpenShift on IBM Cloud in normal usage. If you run privileged containers, run commands on the workers, or execute untrusted code, then you might be at risk.
Master patch updates are applied automatically. Worker node patch updates can be applied by reloading or updating the worker nodes. For more information about major, minor, and patch versions and preparation actions between minor versions, see Red Hat OpenShift versions.
Version 4.21
Master fix pack 4.21.18_1520_openshift, released 26 June 2026
The following table shows the components that are in the master fix pack 4.21.18_1520_openshift. Master patch updates are applied automatically.
| Component | Description |
|---|---|
| Cluster health image v1.6.16 | New version contains updates and security fixes. |
| etcd v3.5.30 | See the etcd release notes. |
| IBM Cloud Block Storage driver and plug-in v2.5.26 | New version contains updates and security fixes. |
| IBM Cloud Controller Manager v1.34.8-2 | New version contains updates and security fixes. |
| IBM Cloud File Storage for Classic plug-in and monitor v455 | New version contains updates and security fixes. |
| Key Management Service provider 2.10.25 | New version contains updates and security fixes. |
| Portieris admission controller v0.14.0 | See the Portieris admission controller release notes |
| Red Hat OpenShift on IBM Cloud 4.21.18 | See the Red Hat OpenShift on IBM Cloud release notes. |
Worker node fix pack 4.21.19_1521_openshift, released 15 June 2026
The following table shows the components included in the worker node fix pack 4.21.19_1521_openshift. Worker node patch updates can be applied by updating, reloading (in classic infrastructure), or replacing (in VPC infrastructure) the worker node.
| Component | Description |
|---|---|
| RHEL 9 (VPC) 5.14.0-570.116.1.el9_6 | Resolves the following CVEs: CVE-2026-5119. |
| RHEL 9 (Satellite) 5.14.0-570.62.1.el9_6 | N/A |
| RHEL 9 (Classic) 5.14.0-570.116.1.el9_6 | N/A |
| Red Hat OpenShift 4.21.19 | For more information, see the change logs. |
| Red Hat CoreOS 4.21.19 | For more information, see the change logs. |
| HAProxy d4656f400ca14059e1b5b8ef8078b4903290791a | Resolves the following CVEs: CVE-2026-45186. |
Worker node fix pack 4.21.17_1519_openshift, released 03 June 2026
The following table shows the components included in the worker node fix pack 4.21.17_1519_openshift. Worker node patch updates can be applied by updating, reloading (in classic infrastructure), or replacing (in VPC infrastructure) the worker node.
Master fix pack 4.21.15_1517_openshift, released 22 May 2026
The following table shows the components that are in the master fix pack 4.21.15_1517_openshift. Master patch updates are applied automatically.
| Component | Description |
|---|---|
| IBM Cloud Controller Manager v1.34.7-4 | New version contains updates and security fixes. |
| Key Management Service provider 2.10.24 | New version contains updates and security fixes. |
| Kubernetes feature gates configuration | RotateKubeletServerCertificate=true,BuildCSIVolumes=true,NetworkLiveMigration=true,OpenShiftPodSecurityAdmission=false,AdminNetworkPolicy=true,KMSv1=false,ExternalOIDC=true,NetworkDiagnosticsConfig=true,ManagedBootImages=true,TranslateStreamCloseWebsocketRequests=false,NewOLM=false,DisableNodeKubeProxyVersion=false,ServiceAccountTokenNodeBinding=true,AdditionalRoutingCapabilities=true,CPMSMachineNamePrefix=true,ConsolePluginContentSecurityPolicy=true,GatewayAPI=true,GatewayAPIController=true,MetricsCollectionProfiles=true,NetworkSegmentation=true,RouteExternalCertificate=true,HighlyAvailableArbiter=true,ImageVolume=true,MachineConfigNodes=true,PinnedImages=true,ProcMountType=true,RouteAdvertisements=true,SigstoreImageVerification=true,StoragePerformantSecurityPolicy=true,UpgradeStatus=true,UserNamespacesPodSecurityStandards=true,UserNamespacesSupport=true,ExternalOIDCWithUIDAndExtraClaimMappings=true,HyperShiftOnlyDynamicResourceAllocation=true,ImageStreamImportMode=true,ManagedBootImagesvSphere=true,PreconfiguredUDNAddresses=true,SigstoreImageVerificationPKI=true,VolumeAttributesClass=true. For more information, see Kubernetes docs |
| Portieris admission controller v0.13.38 | See the Portieris admission controller release notes |
| Red Hat OpenShift on IBM Cloud 4.21.15 | See the Red Hat OpenShift on IBM Cloud release notes. |
Worker node fix pack 4.21.15_1518_openshift, released 20 May 2026
The following table shows the components included in the worker node fix pack 4.21.15_1518_openshift. Worker node patch updates can be applied by updating, reloading (in classic infrastructure), or replacing (in VPC infrastructure) the worker node.
Change log for master fix pack 4.21.13_1516_openshift, released 13 May 2026
The following table shows the changes that are in the master fix pack 4.21.13_1516_openshift. Master patch updates are applied automatically.
| Component | Previous | Current | Description |
|---|---|---|---|
| IBM Cloud Controller Manager | v1.33.10-2 | v1.34.7-1 | New version contains updates and security fixes. |
| Kubernetes pause container | 3.10.1 | 3.10.2 | New version contains updates and security fixes. |
| Red Hat OpenShift | 4.20.18 | 4.21.13 | See the Red Hat OpenShift on IBM Cloud release notes. |
Change log for worker node fix pack 4.21.10_1514_openshift, released 13 May 2026
The following table shows the changes that are in the worker node fix pack 4.21.10_1514_openshift. Worker node patch updates can be applied by updating, reloading (in classic infrastructure), or replacing (in VPC infrastructure) the worker node.
| Component | Previous | Current | Description |
|---|---|---|---|
| Red Hat OpenShift | 4.20.15 | 4.21.10 | See the Red Hat OpenShift on IBM Cloud release notes. |