RHSA-2026:34764: Important: OpenShift Container Platform 4.21.23 bug fix and security update

Red Hat OpenShift Container Platform is Red Hat's cloud computing Kubernetes application platform solution designed for on-premise or private cloud deployments.This advisory contains the container images for Red Hat OpenShift Container Platform 4.21.23. See the following advisory for the RPM packages for this release:https://access.redhat.com/errata/RHBA-2026:34759 Space precludes documenting all of the container images in this advisory. See the following Release Notes documentation, which will be updated shortly for this release, for details about these changes:https://docs.redhat.com/en/documentation/openshiftcontainerplatform/4.21/html/releasenotes/ Security Fix(es): gnutls: gnutls: Denial of Service via DTLS packet reordering vulnerability (CVE-2026-42009) gnutls: gnutls: Authentication Bypass via NUL Character in Username (CVE-2026-42010) kernel: Linux kernel: smb: client: reject userspace cifs.spnego descriptions (CVE-2026-46243) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.All OpenShift Container Platform 4.21 users are advised to upgrade to these updated packages and images when they are available in the appropriate release channel. To check for available updates, use the OpenShift CLI (oc) or web console. Instructions for upgrading a cluster are available at https://docs.redhat.com/en/documentation/openshiftcontainerplatform/4.21/html-single/updatingclusters/index#updating-cluster-cli.

— Red Hat