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Fencer Vulns
medium 6.1

CVE-2026-56858 json

Fix Javascript regexp context tracking in html/template

published 2026-08-13 2 mo ago modified 2026-10-20 20 d ago also BIT-golang-2026-56858 , EUVD-2026-58512 , GO-2026-6091

cvss
6.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 23%
public exploits
0
none known

Summary

Previously, pathological inputs could close an unescaped '/' early, allowing for attack-controlled data to inject arbitrary content, potentially leading to XSS.

Patch / fix

  • bitnami golang 1.25.13, 1.26.6, 1.27.0
  • go stdlib 1.25.13, 1.26.6, 1.27.0-rc.3
  • Go standard library html/template 1.25.13, 1.26.6, 1.27.0-rc.3
  • golang-1.26 Debian 14 1.26.6-1
  • golang-1.27 Debian 14 1.27~rc3-1

debian advisories DEBIAN-CVE-2026-56858

  • microshift openshift 4.16 4.16.73-202610151747.p0.g44abd51.assembly.4.16.73.el9
  • microshift-olm openshift 4.16 4.16.73-202610151747.p0.g44abd51.assembly.4.16.73.el9
  • microshift-multus openshift 4.16 4.16.73-202610151747.p0.g44abd51.assembly.4.16.73.el9
  • microshift-selinux openshift 4.16 4.16.73-202610151747.p0.g44abd51.assembly.4.16.73.el9
  • microshift-greenboot openshift 4.16 4.16.73-202610151747.p0.g44abd51.assembly.4.16.73.el9
  • microshift-networking openshift 4.16 4.16.73-202610151747.p0.g44abd51.assembly.4.16.73.el9
  • microshift-release-info openshift 4.16 4.16.73-202610151747.p0.g44abd51.assembly.4.16.73.el9
  • microshift-olm-release-info openshift 4.16 4.16.73-202610151747.p0.g44abd51.assembly.4.16.73.el9

red hat advisories RHSA-2026:83631RHSA-2026:80167RHSA-2026:74797RHSA-2026:76795RHSA-2026:76809RHSA-2026:74796

  • govulncheck-vulndb SLES for SAP applications 16.0, SLES 16.0 0.0.20260827T195228-160000.1.1
  • go1.26-openssl SLES for SAP applications 16.0, SLES 16.0 1.26.7-160000.1.1
  • go1.25-openssl SLES for SAP applications 16.0, SLES 16.0 1.25.14-160000.1.1
  • go1.27 SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 1.27.0-150000.1.6.1
  • go1.26-openssl SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Development Tools 15 SP7 1.26.7-150600.13.15.1
  • go1.25-openssl SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Development Tools 15 SP7 1.25.14-150600.13.27.1
  • go1.25-openssl SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +5 more 1.25.14-150000.1.33.1
  • go1.26-openssl SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +5 more 1.26.7-150000.1.18.1

suse advisories SUSE-SU-2026:23625-1SUSE-SU-2026:23576-1SUSE-SU-2026:23573-1SUSE-SU-2026:3830-1SUSE-SU-2026:3816-1SUSE-SU-2026:3815-1

  • rclone openSUSE Leap 16.0 1.75.1-bp160.1.1
  • rclone openSUSE Tumbleweed 1.75.1-1.1
  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260827T195228-160000.1.1
  • go1.26-openssl openSUSE Leap 16.0 1.26.7-160000.1.1
  • go1.25-openssl openSUSE Leap 16.0 1.25.14-160000.1.1
  • go1.26 openSUSE Leap 16.0 1.26.6-160000.1.1
  • go1.25 openSUSE Leap 16.0 1.25.13-160000.1.1
  • go1.27 openSUSE Tumbleweed 1.27rc3-1.1

opensuse advisories openSUSE-SU-2026:21999-1openSUSE-SU-2026:11727-1openSUSE-SU-2026:21761-1openSUSE-SU-2026:21705-1openSUSE-SU-2026:21696-1openSUSE-SU-2026:21593-1

  • buildah AlmaLinux 9 2:1.43.3-2.el9_8
  • buildah-tests AlmaLinux 9 2:1.43.3-2.el9_8
  • skopeo AlmaLinux 9 2:1.22.2-8.el9_8
  • skopeo-tests AlmaLinux 9 2:1.22.2-8.el9_8
  • podman AlmaLinux 9 6:5.8.2-7.el9_8
  • podman-tests AlmaLinux 9 6:5.8.2-7.el9_8
  • podman-docker AlmaLinux 9 6:5.8.2-7.el9_8
  • podman-remote AlmaLinux 9 6:5.8.2-7.el9_8

almalinux advisories ALSA-2026:70640ALSA-2026:70641ALSA-2026:69961ALSA-2026:70201ALSA-2026:70391ALSA-2026:66016

  • buildah Rocky Linux 9 2:1.43.3-2.el9_8
  • skopeo Rocky Linux 9 2:1.22.2-8.el9_8
  • podman Rocky Linux 10 7:5.8.2-9.el10_2
  • podman Rocky Linux 9 6:5.8.2-7.el9_8
  • containernetworking-plugins Rocky Linux 9 1:1.9.0-4.el9_8
  • osbuild-composer Rocky Linux 8 101.5-2.el8_10.rocky.0.6
  • osbuild-composer Rocky Linux 10 165.1-3.el10_2.2.rocky.0.1
  • image-builder Rocky Linux 9 52.1-1.el9_8.2

rocky linux advisories RLSA-2026:70640RLSA-2026:70641RLSA-2026:70201RLSA-2026:69961RLSA-2026:70391RLSA-2026:66016

  • go Alpine 3.24 1.26.8-r0

alpine advisories ALPINE-CVE-2026-56858

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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-2026-56858 updated cvss 8.1

html/template: golang: Go html/template: Cross-Site Scripting via pathological input

  • Red Hat Assisted Installer for Red Hat OpenShift Container Platform 2 rhai/assisted-installer-rhel9 Red Hat AWS Load Balancer Operator albo/aws-load-balancer-controller-rhel8 Red Hat Confidential Compute Attestation build-of-trustee/trustee-rhel9-operator Red Hat Deployment Validation Operator dvo/deployment-validation-rhel8-operator Red Hat Exploit Intelligence exploit-intelligence-tech-preview/agent-client-rhel9, exploit-intelligence-tech-preview/vulnerability-analysis-rhel9, exploit-intelligence-tech-preview/exploit-intelligence-operator-controller-rhel9 Red Hat ExternalDNS Operator edo/external-dns-rhel9, edo/external-dns-rhel9-operator
    +11 more products
    Red Hat Logical Volume Manager Storage lvms4/topolvm-rhel9 Red Hat Migration Toolkit for Containers rhmtc/openshift-migration-controller-rhel8 Red Hat Multiarch Tuning Operator multiarch-tuning/multiarch-tuning-rhel9-operator Red Hat Multicluster Engine for Kubernetes multicluster-engine/hive-rhel9, multicluster-engine/maestro-rhel9, multicluster-engine/assisted-service-9-rhel9, multicluster-engine/managedcluster-import-controller-rhel9 Red Hat Node Maintenance Operator workload-availability/node-maintenance-operator-bundle Red Hat OpenShift Developer Tools and Services helm 3.20.2.1-75.el9 Red Hat OpenShift Lightspeed openshift-lightspeed/otelcol-lightspeed-rhel9 Red Hat OpenShift Pipelines openshift-pipelines-client 1.22.0-11814.el9, openshift-pipelines/pipelines-scheduler-rhel9 Red Hat OpenShift Serverless kn-workflow-plugin 1.38.0-3.el9, openshift-serverless-clients 1.17.0-4.el9, openshift-serverless-1/kn-plugin-event-sender-rhel9 Red Hat OpenShift Service Mesh 3 openshift-golang-builder-container Red Hat Power monitoring for Red Hat OpenShift openshift-power-monitoring/kepler-rhel9
    affected: workaround, no fix available
  • Red Hat Advanced Cluster Management for Kubernetes 2 flightctl-agent, flightctl-selinux, rhacm2/subctl-rhel9, flightctl 0.10.0-1.el9em
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat AI Inference Server rhaiis/vllm-cpu-rhel9, rhaiis/vllm-tpu-rhel9
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Ansible Automation Platform 2 ansible-automation-platform-27/receptor-rhel9
    affected: workaround, no fix available
  • Red Hat Ceph Storage 5 rhceph/snmp-notifier-rhel8 Red Hat Ceph Storage 6 rhceph/snmp-notifier-rhel9 Red Hat Ceph Storage 7 rhceph/grafana-rhel9 Red Hat Ceph Storage 8 libarrow, parquet-libs, python3-pyarrow, parquet-glib-libs, libarrow-glib-libs, libarrow-python-libs, +3 more Red Hat Ceph Storage 9 libarrow, parquet-libs, rhceph/alloy-rhel10
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Certification Program for Red Hat Enterprise Linux 9 redhat-certification-cnf 9.0-20240522.1.el9, redhat-certification-preflight 9.37-20260618.el9 Red Hat Connectivity Link 1 rhcl-1/coredns-rhel9 Red Hat Enterprise Linux 7 rhc Red Hat Enterprise Linux 8 rhc Red Hat Enterprise Linux 9 delve, ignition, ignition-edge, ignition-grub, gvisor-tap-vsock, ignition-validate, +3 more Red Hat Enterprise Linux 10 rhc, delve, ignition 2.26.0-2.el10_2, gvisor-tap-vsock 0.8.7-1.el10
    +3 more products
    Red Hat Enterprise Linux AI (RHEL AI) 3 golang 1.25.1-1.el9 Red Hat OpenShift AI (RHOAI) rhoai/odh-dashboard-rhel9, rhoai/odh-kueue-controller-rhel9, rhoai/odh-ml-pipelines-driver-rhel9, rhoai/odh-ml-pipelines-launcher-rhel9, rhoai/odh-llm-d-batch-gateway-gc-rhel9, rhoai/odh-model-registry-operator-rhel9, +14 more Red Hat OpenShift Cluster Manager CLI ocm-cli-clients/ocm-cli-rhel9
    affected: workaround, no fix available
  • Red Hat OpenShift Container Platform 4 podman, skopeo, ignition, podman-tests, skopeo-tests, podman-docker, +10 more Red Hat OpenShift Container Platform 5 cri-tools 1.35.0-2.el9, openshift5/ose-kube-rbac-proxy-rhel9, cri-o 1.35.5-3.rhaos4.22.git0adf62b.el9, openshift 4.22.0-202608010430.p2.g5f1e0e7.assembly.stream.el9, openshift-clients 4.22.0-202607132126.p2.g7ec2e14.assembly.stream.el9, ose-gcp-gcr-image-credential-provider 4.22.0-202604110549.p2.g4d9707e.assembly.stream.el8, +1 more
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat OpenShift for Windows Containers openshift4-wincw/windows-machine-config-rhel9-operator
    affected: workaround, no fix available
show 2 more
  • Red Hat OpenShift GitOps openshift-gitops-1/dex-rhel8, openshift-gitops-1/dex-rhel9, microshift-gitops 1.19.2-36.el9
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat OpenShift on AWS rosa 1.2.64-b2f7c89.el8 Red Hat OpenShift Virtualization 4 openshift-golang-builder-container
    affected: workaround, no fix available

5 more affected, 114 more fixed, 111 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
2 mo ago

Exploit prediction

0.31% chance of exploitation in the next 30 days, higher than 23% 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
OSV 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
bitnami golang
<1.25.13
>=1.26.0-0, <1.26.6
>=1.27.0-0, <1.27.0
1.25.13
1.26.6
1.27.0
go stdlib
<1.25.13
>=1.26.0-0, <1.26.6
>=1.27.0-0, <1.27.0-rc.3
1.25.13
1.26.6
1.27.0-rc.3

Affected products

  • Go standard library html/template

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

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.