RHSA-2026:90332HighCVSS 8.1

Red Hat Security Advisory: RHOSO 18.0 os-diff security update

Published
October 26, 2026
Last Modified
November 3, 2026

🔗 CVE IDs covered (12)

CVE-2026-97031 →CVE-2026-111943 →CVE-2026-56853 →CVE-2026-56858 →CVE-2026-56860 →CVE-2026-56862 →CVE-2026-78669 →CVE-2026-27145 →CVE-2026-33818 →CVE-2026-42504 →CVE-2026-78667 →CVE-2026-94440 →

📋 Description

CVE-2026-27145 — crypto/x509: golang: golang crypto/x509: Denial of Service via excessive processing of DNS SAN entries CVE-2026-33818 — encoding/asn1: golang: Go encoding/asn1: Denial of Service via excessive recursion in Unmarshal CVE-2026-42504 — mime: golang: Golang MIME: Denial of Service via maliciously-crafted MIME header CVE-2026-56853 — net/http: golang: Go net/http: Unencrypted HTTP/2 connections vulnerable to Denial of Service CVE-2026-56858 — html/template: golang: Go html/template: Cross-Site Scripting via pathological input 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 CVE-2026-78667 — net/http: golang: golang: Denial of Service via crafted HTTP Range headers CVE-2026-78669 — net/http: net/http/internal/http2: golang.org/x/net/http2: net/http: Denial of Service via excessive HTTP/2 SETTINGS frames CVE-2026-94440 — net/textproto: mime/multipart: golang: golang: Denial of Service via memory limit bypass in multipart form parsing CVE-2026-97031 — crypto/tls: golang: crypto/tls: Denial of Service via multiple ECH outer extension references CVE-2026-111943 — crypto/x509: golang: crypto/x509: Man-in-the-middle attacks via untrusted intermediate certificates

🎯 Affected products6

  • 9Base-RHOSO-TOOLS-18
  • Red Hat OpenStack Services on OpenShift 18.0
  • golang-github-openstack-k8s-operators-os-diff-0:0.1.1-18.0.20261021172337.a95ae05.el9ost.src as a component of 9Base-RHOSO-TOOLS-18
  • golang-github-openstack-k8s-operators-os-diff-0:0.1.1-18.0.20261021172337.a95ae05.el9ost.src as a component of Red Hat OpenStack Services on OpenShift 18.0
  • golang-github-openstack-k8s-operators-os-diff-0:0.1.1-18.0.20261021172337.a95ae05.el9ost.x86_64 as a component of 9Base-RHOSO-TOOLS-18
  • golang-github-openstack-k8s-operators-os-diff-0:0.1.1-18.0.20261021172337.a95ae05.el9ost.x86_64 as a component of Red Hat OpenStack Services on OpenShift 18.0

✅ Remediation

Before applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, see “Updating your environment to the latest maintenance release” at https://docs.redhat.com/en/documentation/red_hat_openstack_services_on_openshift/18.0/html/updating_your_environment_to_the_latest_maintenance_release/index Workaround: A flaw was found in the Go standard library crypto/x509 package. When verifying a TLS certificate hostname, VerifyHostname processed each DNS Subject Alternative Name (SAN) entry in a loop and repeatedly split the candidate hostname on "." characters. For certificates with a very large DNS SAN list, CPU use could grow quadratically with the number of SAN entries and hostname labels. Because hostname verification runs before the certificate chain is built, this overhead can occur even when the certificate is not trusted. Red Hat rates this issue as Important. It affects Red Hat products that include the Go standard library crypto/x509 code from an affected Go toolchain version (before Go 1.25.11, or from Go 1.26.0 through Go 1.26.3). Applications and container images built with a fixed Go release (1.25.11 or later, or 1.26.4 or later) are not affected. Community distributions such as Fedora are also affected. Upstream fix: Go 1.25.11 and Go 1.26.4 (GO-2026-5037). 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: 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. Workaround: In case you consume HTTP2, upgrade to a patched version of the http module. Verify: ``` go version go list -m golang.org/x/net govulncheck ./... ``` Workaround: See the security bulletin for a detailed mitigation procedure.

🔗 References (15)