RHSA-2026:74796 - Security Advisory

Topic

Red Hat build of MicroShift release 4.21.36 is now available with updates
to packages and images that include a security update.

Red Hat Product Security has rated this update as having a security impact
of Important. A Common Vulnerability Scoring System (CVSS) base score,
which gives a detailed severity rating, is available for each vulnerability
from the CVE link(s) in the References section.

Description

Red Hat build of MicroShift is Red Hat's light-weight Kubernetes
orchestration solution designed for edge device deployments and is built
from the edge capabilities of Red Hat OpenShift Container Platform.
MicroShift is an application that is deployed on top of Red Hat Enterprise
Linux devices at the edge, providing an efficient way to operate
single-node clusters in these low-resource environments.

This advisory contains the RPM packages for Red Hat build of MicroShift
4.21.36. Read the following advisory for the container images for this
release:

https://access.redhat.com/errata/RHSA-2026:74383

Security Fix(es):

• encoding/asn1: golang: Go encoding/asn1: Denial of Service via excessive

recursion in Unmarshal (CVE-2026-33818)

• mime: golang: Golang MIME: Denial of Service via maliciously-crafted MIME

header (CVE-2026-42504)

• html/template: golang: Go html/template: Cross-Site Scripting via

pathological input (CVE-2026-56858)

• net/url: golang: golang net/url: Denial of Service from quadratic

complexity in path resolution (CVE-2026-56860)

• crypto/tls: golang: Golang crypto/tls: Denial of Service via indefinite

KeyUpdate messages (CVE-2026-56862)

All Red Hat build of MicroShift 4.21 users are advised to use these updated
packages and images when they are available in the RPM repository.

Solution

For MicroShift 4.21, read the following documentation for important
instructions on how to install the latest RPMs and fully apply this
asynchronous errata update:

https://docs.redhat.com/en/documentation/red_hat_build_of_microshift/4.21/html/red_hat_build_of_microshift_release_notes/index

Affected Products

• Red Hat OpenShift Container Platform 4.21 for RHEL 9 x86_64
• Red Hat OpenShift Container Platform for Power 4.21 for RHEL 9 ppc64le
• Red Hat OpenShift Container Platform for IBM Z and LinuxONE 4.21 for RHEL 9 s390x
• Red Hat OpenShift Container Platform for ARM 64 4.21 for RHEL 9 aarch64

Fixes

• BZ - 2484204 - CVE-2026-42504 mime: golang: Golang MIME: Denial of Service via maliciously-crafted MIME header
• BZ - 2515815 - CVE-2026-33818 encoding/asn1: golang: Go encoding/asn1: Denial of Service via excessive recursion in Unmarshal
• BZ - 2515820 - CVE-2026-56860 net/url: golang: golang net/url: Denial of Service from quadratic complexity in path resolution
• BZ - 2515838 - CVE-2026-56858 html/template: golang: Go html/template: Cross-Site Scripting via pathological input
• BZ - 2515839 - CVE-2026-56862 crypto/tls: golang: Golang crypto/tls: Denial of Service via indefinite KeyUpdate messages

CVEs

• CVE-2026-33818
• CVE-2026-42504
• CVE-2026-56858
• CVE-2026-56860
• CVE-2026-56862

References

• https://access.redhat.com/security/updates/classification/#important