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Fencer Vulns
medium 6.1

CVE-2026-27136 json

Invoking duplicate attributes can cause XSS in golang.org/x/net/html

published 2026-05-22 5 mo ago modified 2026-09-22 47 d ago also EUVD-2026-31451 , GO-2026-5030

cvss
6.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 13%
public exploits
0
none known

Summary

Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering.

Patch / fix

  • go golang.org/x/net 0.55.0
  • golang.org/x/net golang.org/x/net/html 0.55.0
  • golang-golang-x-net Debian 14 1:0.55.0-1

debian advisories DEBIAN-CVE-2026-27136

  • osbuild-composer RHEL 9 165.1-5.el9_8
  • osbuild-composer-core RHEL 9 165.1-5.el9_8
  • osbuild-composer-worker RHEL 9 165.1-5.el9_8
  • golang1.27 hummingbird 1 1.27.1-0.1.hum1
  • golang1.27-bin hummingbird 1 1.27.1-0.1.hum1
  • golang1.27-src hummingbird 1 1.27.1-0.1.hum1
  • golang1.27-misc hummingbird 1 1.27.1-0.1.hum1
  • golang1.27-tests hummingbird 1 1.27.1-0.1.hum1

red hat advisories RHSA-2026:69293RHSA-2026:66561RHSA-2026:62391RHSA-2026:68334RHSA-2026:67517RHSA-2026:67138

  • containerized-data-importer SLE Module for Containers 15 SP7 1.64.0-150700.9.14.1
  • grafana SLE Module for Package Hub 15 SP7 12.4.5-150200.3.91.1
  • kubevirt-1.6 SLE Module for Containers 15 SP7 1.6.6-150700.15.17.1
  • kubevirt SLE Module for Containers 15 SP7 1.7.4-150700.3.30.1
  • terraform-provider-aws SLE Module for Public Cloud 15 SP5, SLE Module for Public Cloud 15 SP4 3.11.0-150200.6.18.1
  • terraform-provider-tls SLE Module for Public Cloud 15 SP5, SLE Module for Public Cloud 15 SP4 3.0.0-150200.5.15.1
  • terraform-provider-helm SLE Module for Public Cloud 15 SP5, SLE Module for Public Cloud 15 SP4 2.9.0-150200.6.23.1
  • terraform-provider-null SLE Module for Public Cloud 15 SP5, SLE Module for Public Cloud 15 SP4 3.0.0-150200.6.18.1

suse advisories SUSE-SU-2026:4209-1SUSE-SU-2026:3718-1SUSE-SU-2026:3630-1SUSE-SU-2026:3203-1SUSE-SU-2026:3056-1SUSE-SU-2026:22613-1

  • containerized-data-importer1.65 openSUSE Leap 16.0 1.65.0-160000.3.1
  • glab openSUSE Leap 16.0 1.114.0-bp160.1.1
  • kubevirt1.8 openSUSE Leap 16.0 1.8.4-160000.1.1
  • containerized-data-importer1.66 openSUSE Tumbleweed 1.66.0-1.1
  • kubevirt1.9 openSUSE Tumbleweed 1.9.0-1.1
  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1
  • rclone openSUSE Leap 16.0 1.74.4-bp160.1.1
  • kubevirt1.8 openSUSE Tumbleweed 1.8.4-2.1

opensuse advisories openSUSE-SU-2026:21824-1openSUSE-SU-2026:21662-1openSUSE-SU-2026:21590-1openSUSE-SU-2026:11514-1openSUSE-SU-2026:11520-1openSUSE-SU-2026:21483-1

  • osbuild-composer AlmaLinux 9 165.1-5.el9_8.alma.1
  • osbuild-composer-core AlmaLinux 9 165.1-5.el9_8.alma.1
  • osbuild-composer-worker AlmaLinux 9 165.1-5.el9_8.alma.1
  • osbuild-composer AlmaLinux 10 165.1-5.el10_2.alma.1
  • osbuild-composer-core AlmaLinux 10 165.1-5.el10_2.alma.1
  • osbuild-composer-worker AlmaLinux 10 165.1-5.el10_2.alma.1
  • podman AlmaLinux 9 6:5.8.2-4.el9_8
  • podman-tests AlmaLinux 9 6:5.8.2-4.el9_8

almalinux advisories ALSA-2026:69293ALSA-2026:66432ALSA-2026:37123

  • osbuild-composer Rocky Linux 9 165.1-5.el9_8.rocky.0.1
  • image-builder Rocky Linux 9 52.1-2.el9_8
  • image-builder Rocky Linux 10 52.1-2.el10_2.rocky.0.1
  • osbuild-composer Rocky Linux 10 165.1-5.el10_2.rocky.0.1
  • podman Rocky Linux 10 7:5.8.2-4.el10_2
  • podman Rocky Linux 9 6:5.8.2-4.el9_8

rocky linux advisories RLSA-2026:69293RLSA-2026:67138RLSA-2026:67139RLSA-2026:66432RLSA-2026:37072RLSA-2026:37123

  • application-gateway-kubernetes-ingress Azure Linux 3.0 1.7.7-5
  • cert-manager Azure Linux 3.0 1.12.15-9
  • cf-cli Azure Linux 3.0 8.7.11-6
  • cloud-provider-kubevirt Azure Linux 3.0 0.5.1-4
  • cni-plugins Azure Linux 3.0 1.4.0-6
  • containerd2 Azure Linux 3.0 2.2.4-2
  • containerized-data-importer Azure Linux 3.0 1.62.0-6
  • cri-tools Azure Linux 3.0 1.32.0-6

azure linux advisories AZL-87375AZL-87426AZL-87471AZL-87495AZL-87507AZL-87534

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-27136 updated cvss 8.1

golang.org/x/net/html: golang: golang.org/x/net/html: Cross-Site Scripting via HTML parsing bypass

  • Red Hat Assisted Installer for Red Hat OpenShift Container Platform 2 rhai/assisted-installer-rhel9, rhai/assisted-installer-agent-rhel9, rhai/assisted-installer-controller-rhel9, assisted/agent-preinstall-image-builder-rhel9 Red Hat cert-manager Operator for Red Hat OpenShift cert-manager/cert-manager-trust-manager-rhel9 Red Hat Compliance Operator compliance/openshift-compliance-operator-bundle
    affected: workaround, no fix available
  • Red Hat Confidential Compute Attestation openshift-sandboxed-containers/osc-rhel9-operator, openshift-sandboxed-containers/osc-podvm-payload-rhel9, openshift-sandboxed-containers/osc-cloud-api-adaptor-rhel9
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Cryostat 4 cryostat/cryostat-rhel9-operator
    affected: workaround, no fix available
  • Red Hat External Secrets Operator for Red Hat OpenShift external-secrets-operator/external-secrets-rhel9
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Fence Agents Remediation Operator workload-availability/fence-agents-remediation-rhel8-operator, workload-availability/fence-agents-remediation-operator-bundle, redhat-user-workloads/rhwa-tenant/fence-agents-remediation/far-operator-0-8 Red Hat File Integrity Operator compliance/openshift-file-integrity-operator-bundle Red Hat Machine Deletion Remediation Operator redhat-user-workloads/rhwa-tenant/machine-deletion-remediation/mdr-operator-0-7
    affected: workaround, no fix available
  • Red Hat Migration Toolkit for Applications 8 mta/mta-hub-rhel8, mta/mta-dotnet-external-provider-rhel8, mta/mta-dotnet-external-provider-rhel9
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Multiarch Tuning Operator multiarch-tuning/multiarch-tuning-rhel9-operator, multiarch-tuning/multiarch-tuning-operator-bundle Red Hat Multicluster Engine for Kubernetes multicluster-engine/assisted-installer-rhel8, multicluster-engine/assisted-installer-rhel9, multicluster-engine/assisted-service-8-rhel8, multicluster-engine/assisted-service-9-rhel9, multicluster-engine/azure-service-operator-rhel9, multicluster-engine/mce-capi-webhook-config-rhel9, +8 more Red Hat Node HealthCheck Operator workload-availability/node-healthcheck-rhel8-operator, workload-availability/node-healthcheck-operator-bundle, node-healthcheck-operator-tech-preview/node-healthcheck-operator-rhel8, node-healthcheck-operator-tech-preview/node-healthcheck-rhel8-operator, node-healthcheck-operator-tech-preview/node-healthcheck-operator-bundle, redhat-user-workloads/rhwa-tenant/node-healthcheck-operator/nhc-operator-0-12 Red Hat Node Maintenance Operator redhat-user-workloads/rhwa-tenant/node-maintenance-operator/nmo-operator-5-7 Red Hat OpenShift Developer Tools and Services helm Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-rhel9-operator
    +2 more products
    Red Hat OpenShift Pipelines openshift-pipelines-client, openshift-pipelines/pipelines-cli-tkn-rhel9, openshift-pipelines/pipelines-chains-controller-rhel9, openshift-pipelines/pipelines-pipelines-as-code-watcher-rhel9, openshift-pipelines/pipelines-pipelines-as-code-webhook-rhel9, openshift-pipelines/pipelines-pipelines-as-code-controller-rhel9 Red Hat OpenShift Serverless kn-workflow-plugin, openshift-serverless-clients, openshift-serverless-1/logic-rhel9-operator, openshift-serverless-1/kn-plugin-func-func-util-rhel9
    affected: workaround, no fix available
  • Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/acm-grafana-rhel9, rhacm2/search-collector-rhel9, rhacm2/submariner-addon-rhel9, rhacm2/multicloud-integrations-rhel9, rhacm2/multicluster-operators-subscription-rhel9
    affected: workaround, no fix available, no fix planned “Will not fix”
show 8 more
  • Red Hat Advanced Cluster Security 4 advanced-cluster-security/rhacs-main-rhel8, advanced-cluster-security/rhacs-roxctl-rhel8, advanced-cluster-security/rhacs-scanner-rhel8, advanced-cluster-security/rhacs-rhel8-operator, advanced-cluster-security/rhacs-scanner-v4-rhel8, advanced-cluster-security/rhacs-scanner-slim-rhel8 Red Hat Connectivity Link 1 rhcl-1/developer-portal-controller-rhel9 Red Hat Enterprise Linux 8 osbuild-composer, osbuild-composer-core, osbuild-composer-worker, osbuild-composer-dnf-json Red Hat Enterprise Linux 9 grafana, grafana-selinux, gvisor-tap-vsock, opentelemetry-collector, gvisor-tap-vsock-gvforwarder Red Hat Enterprise Linux 10 grafana, gvisor-tap-vsock, opentelemetry-collector
    affected: workaround, no fix available
  • Red Hat Hardened Images golang1.25
    affected: workaround, no fix planned “Will not fix”
  • Red Hat OpenShift AI (RHOAI) rhoai/rhai-cli-rhel9, rhoai/odh-codeflare-operator-rhel9, rhoai/odh-modelmesh-serving-controller-rhel9, rhoai/odh-workload-variant-autoscaler-controller-rhel9 Red Hat OpenShift Cluster Manager CLI ocm-cli-clients/ocm-cli-rhel9
    affected: workaround, no fix available
  • Red Hat OpenShift Container Platform 4 openshift4/ose-cli-rhel9, openshift4/ose-tools-rhel9, openshift4/ose-dpu-cni-rhel9, openshift4/ose-dpu-daemon-rhel9, openshift4/ose-dpu-rhel9-operator, openshift4/ose-operator-sdk-rhel8, +21 more Red Hat OpenShift Container Platform 5 cri-o, openshift, openshift5/ose-dpu-cni-rhel9, openshift5/ose-hyperkube-rhel9, openshift5/ose-dpu-daemon-rhel9, openshift5/ose-hypershift-rhel9, +39 more
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat OpenShift Dev Workspaces Operator devworkspace/devworkspace-rhel9-operator, devworkspace/devworkspace-project-clone-rhel9 Red Hat OpenShift distributed tracing 3 rhosdt/tempo-rhel9, rhosdt/tempo-query-rhel9, rhosdt/tempo-jaeger-query-rhel9, rhosdt/opentelemetry-collector-rhel9
    affected: workaround, no fix available
  • Red Hat OpenShift GitOps openshift-gitops-1/argocd-rhel8, openshift-gitops-1/argocd-rhel9, openshift-gitops-1/gitops-rhel8, openshift-gitops-1/gitops-rhel9, openshift-gitops-1/gitops-rhel8-operator, openshift-gitops-1/argocd-image-updater-rhel8, +1 more
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat OpenShift on AWS rosa Red Hat OpenShift Virtualization 4 kubevirt Red Hat Trusted Artifact Signer rhtas/ec-rhel9, rhtas/model-validation-agent-rhel9, rhtas/model-validation-rhel9-operator, rhtas/policy-controller-rhel9-operator Red Hat Security Profiles Operator compliance/openshift-selinuxd-rhel8, compliance/openshift-selinuxd-rhel9, compliance/openshift-selinuxd-rhel10 Red Hat Self Node Remediation Operator redhat-user-workloads/rhwa-tenant/self-node-remediation/snr-operator-0-13 Red Hat Storage-Based Remediation redhat-user-workloads/rhwa-tenant/storage-based-remediation/sbr-operator-0-3
    affected: workaround, no fix available
  • Red Hat Zero Trust Workload Identity Manager zero-trust-workload-identity-manager/zero-trust-workload-identity-manager-rhel9 Red Hat Zero Trust Workload Identity Manager - Tech Preview zero-trust-workload-identity-manager/zero-trust-workload-identity-manager-rhel9
    affected: workaround, no fix planned “Will not fix”

77 more fixed, 83 more not affected in the full advisory

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CNA 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
go golang.org/x/net
<0.55.0
0.55.0

Affected products

  • golang.org/x/net golang.org/x/net/html

Classification

Weakness
  • CWE-1021 Improper Restriction of Rendered UI Layers or Frames

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.