RHSA-2026:66350HighCVSS 8.2

Red Hat Security Advisory: OpenShift Container Platform 4.21.33 packages and security update

Published
September 15, 2026
Last Modified
September 18, 2026

🔗 CVE IDs covered (8)

CVE-2026-33818 →CVE-2026-39821 →CVE-2026-39822 →CVE-2026-42504 →CVE-2026-56859 →CVE-2026-56860 →CVE-2026-56862 →CVE-2026-33814 →

📋 Description

CVE-2026-33814 — net/http/internal/http2: golang: golang.org/x/net: Go HTTP/2: Denial of Service via malformed SETTINGS_MAX_FRAME_SIZE frame CVE-2026-33818 — encoding/asn1: golang: Go encoding/asn1: Denial of Service via excessive recursion in Unmarshal CVE-2026-39821 — golang.org/x/net/idna: golang: net/http: golang.org/x/net/idna: Privilege escalation via incorrect Punycode label processing CVE-2026-39822 — golang: Go os.Root: Symlink following vulnerability allows directory traversal CVE-2026-42504 — mime: golang: Golang MIME: Denial of Service via maliciously-crafted MIME header CVE-2026-56859 — encoding/xml: golang: Go: Denial of Service via XML decoding recursion depth issue CVE-2026-56860 — net/url: golang: golang net/url: Denial of Service from quadratic complexity in path resolution CVE-2026-56862 — crypto/tls: golang: Golang crypto/tls: Denial of Service via indefinite KeyUpdate messages

🎯 Affected products94

  • Red Hat OpenShift Container Platform 4.21
  • haproxy-0:2.8.10-3.rhaos4.21.el9.src as a component of Red Hat OpenShift Container Platform 4.21
  • haproxy-debugsource-0:2.8.10-3.rhaos4.21.el9.aarch64 as a component of Red Hat OpenShift Container Platform 4.21
  • haproxy-debugsource-0:2.8.10-3.rhaos4.21.el9.ppc64le as a component of Red Hat OpenShift Container Platform 4.21
  • haproxy-debugsource-0:2.8.10-3.rhaos4.21.el9.s390x as a component of Red Hat OpenShift Container Platform 4.21
  • haproxy-debugsource-0:2.8.10-3.rhaos4.21.el9.x86_64 as a component of Red Hat OpenShift Container Platform 4.21
  • haproxy28-0:2.8.10-3.rhaos4.21.el9.aarch64 as a component of Red Hat OpenShift Container Platform 4.21
  • haproxy28-0:2.8.10-3.rhaos4.21.el9.ppc64le as a component of Red Hat OpenShift Container Platform 4.21
  • haproxy28-0:2.8.10-3.rhaos4.21.el9.s390x as a component of Red Hat OpenShift Container Platform 4.21
  • haproxy28-0:2.8.10-3.rhaos4.21.el9.x86_64 as a component of Red Hat OpenShift Container Platform 4.21
  • haproxy28-debuginfo-0:2.8.10-3.rhaos4.21.el9.aarch64 as a component of Red Hat OpenShift Container Platform 4.21
  • haproxy28-debuginfo-0:2.8.10-3.rhaos4.21.el9.ppc64le as a component of Red Hat OpenShift Container Platform 4.21
  • haproxy28-debuginfo-0:2.8.10-3.rhaos4.21.el9.s390x as a component of Red Hat OpenShift Container Platform 4.21
  • haproxy28-debuginfo-0:2.8.10-3.rhaos4.21.el9.x86_64 as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-0:4.21.0-202609022229.p2.g93afd70.assembly.stream.el10.src as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-0:4.21.0-202609022229.p2.g93afd70.assembly.stream.el8.src as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-0:4.21.0-202609022229.p2.g93afd70.assembly.stream.el9.src as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-clients-0:4.21.0-202609071555.p2.gd0bf7cc.assembly.stream.el10.aarch64 as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-clients-0:4.21.0-202609071555.p2.gd0bf7cc.assembly.stream.el10.ppc64le as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-clients-0:4.21.0-202609071555.p2.gd0bf7cc.assembly.stream.el10.s390x as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-clients-0:4.21.0-202609071555.p2.gd0bf7cc.assembly.stream.el10.src as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-clients-0:4.21.0-202609071555.p2.gd0bf7cc.assembly.stream.el10.x86_64 as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-clients-0:4.21.0-202609071555.p2.gd0bf7cc.assembly.stream.el8.aarch64 as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-clients-0:4.21.0-202609071555.p2.gd0bf7cc.assembly.stream.el8.ppc64le as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-clients-0:4.21.0-202609071555.p2.gd0bf7cc.assembly.stream.el8.s390x as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-clients-0:4.21.0-202609071555.p2.gd0bf7cc.assembly.stream.el8.src as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-clients-0:4.21.0-202609071555.p2.gd0bf7cc.assembly.stream.el8.x86_64 as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-clients-0:4.21.0-202609071555.p2.gd0bf7cc.assembly.stream.el9.aarch64 as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-clients-0:4.21.0-202609071555.p2.gd0bf7cc.assembly.stream.el9.ppc64le as a component of Red Hat OpenShift Container Platform 4.21
  • openshift-clients-0:4.21.0-202609071555.p2.gd0bf7cc.assembly.stream.el9.s390x as a component of Red Hat OpenShift Container Platform 4.21
  • +64 more not shown

✅ Remediation

For OpenShift Container Platform 4.21 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/4.21/html/release_notes/ Workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. Workaround: Upgrade to a fixed golang.org/x/net release that includes the idna correction, via updated golang or dependent package rebuilds. Workaround: There is no mitigation for this issue other than updating the Go toolchain to Go 1.25.12 or Go 1.26.5. Programs compiled with Go >= 1.24 that do not use the os.Root API are not affected by this vulnerability. The os.Root API was introduced in Go 1.24. Go versions prior to 1.24 are not affected. This issue is fixed in Go 1.25.12 and Go 1.26.5. Workaround: To mitigate this issue, restrict network access to services that process MIME headers from untrusted sources. Implement input validation and sanitization for all incoming data, especially MIME headers, to prevent maliciously crafted content from being processed by applications utilizing the vulnerable Golang MIME package.

🔗 References (11)