RHSA-2026:21656HighCVSS 7.8

Red Hat Security Advisory: OpenShift Container Platform 4.18.43 bug fix and security update

Published
June 3, 2026
Last Modified
August 21, 2026

🔗 CVE IDs covered (4)

CVE-2026-27135 →CVE-2026-35535 →CVE-2026-43503 →CVE-2026-46300 →

📋 Description

CVE-2026-27135 — nghttp2: nghttp2: Denial of Service via malformed HTTP/2 frames after session termination CVE-2026-35535 — sudo: Sudo: Privilege escalation due to failure in privilege drop calls CVE-2026-43503 — kernel: net: skbuff: propagate shared-frag marker through frag-transfer helpers CVE-2026-46300 — kernel: "Fragnesia" is a variant of Dirty Frag vulnerability in the ESP/XFRM leading to Local Privilege Escalation (LPE) vulnerability in the Linux kernel

🎯 Affected products5

  • Red Hat OpenShift Container Platform 4.18
  • rhcos-aarch64-418.94.202605260517-0 as a component of Red Hat OpenShift Container Platform 4.18
  • rhcos-ppc64le-418.94.202605260517-0 as a component of Red Hat OpenShift Container Platform 4.18
  • rhcos-s390x-418.94.202605260517-0 as a component of Red Hat OpenShift Container Platform 4.18
  • rhcos-x86_64-418.94.202605260517-0 as a component of Red Hat OpenShift Container Platform 4.18

✅ Remediation

For OpenShift Container Platform 4.18 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.18/html/release_notes/ You may download the oc tool and use it to inspect release image metadata for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests may be found at https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags. The sha values for the release are as follows: (For x86_64 architecture) The image digest is sha256:27eafee2d15ebe7d66cf14aeefbb79f91512669ecee1facf3ee5f06019dca651 (For s390x architecture) The image digest is sha256:928917977895d721b3355e93031ae9da26e0e34f4f4fa1aee5723a22ab98432d (For ppc64le architecture) The image digest is sha256:12d6af49e535ddf1a786f40c18e2bc195ca21602cfdd37552fcdb762c6d00922 (For aarch64 architecture) The image digest is sha256:d84590b666012baf94ad1dd3216779f5e851da6571702b2440b9071a5d1e9f55 All OpenShift Container Platform 4.18 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/openshift_container_platform/4.18/html-single/updating_clusters/index#updating-cluster-cli. Workaround: See the security bulletin for a detailed mitigation procedure.

🔗 References (6)