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Fencer Vulns
critical 9.8

CVE-2026-56857 json

Root.Mkdir(All) can follow junctions out of the root on Windows in os

published 2026-10-08 31 d ago modified 2026-10-16 23 d ago also BIT-golang-2026-56857 , EUVD-2026-95420 , GO-2026-6604

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 46%
public exploits
0
none known

Summary

On Windows, when the target of Root.Mkdir or Root.MkdirAll is a junction pointing to an empty location, the operation can create a directory at the junction target even when that target is located outside the root. This only applies to operations where the last path component is a junction (path/to/junction, but not path/junction/target).

Patch / fix

  • bitnami golang 1.26.9, 1.27.2
  • go stdlib 1.26.9, 1.27.2
  • Go standard library os 1.26.9, 1.27.2
  • Go standard library internal/syscall/windows 1.26.9, 1.27.2
  • go1.26-openssl SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +5 more 1.26.10-150000.1.21.2
  • go1.26-openssl SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Development Tools 15 SP7 1.26.10-150600.13.18.1
  • go1.26 SLES for SAP applications 16.0, SLES 16.0 1.26.9-160000.1.1
  • go1.27 SLES for SAP applications 16.0, SLES 16.0 1.27.2-160000.1.1
  • go1.26 SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 1.26.9-150000.1.33.1
  • go1.27 SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 1.27.2-150000.1.12.1

suse advisories SUSE-SU-2026:4867-1SUSE-SU-2026:4866-1SUSE-SU-2026:24239-1SUSE-SU-2026:24237-1SUSE-SU-2026:4629-1SUSE-SU-2026:4625-1

  • tempo-cli openSUSE Tumbleweed 3.1.1-1.1
  • go1.26 openSUSE Leap 16.0 1.26.9-160000.1.1
  • go1.27 openSUSE Leap 16.0 1.27.2-160000.1.1
  • rclone openSUSE Tumbleweed 1.75.2-1.1
  • go1.27 openSUSE Tumbleweed 1.27.2-1.1
  • go1.26 openSUSE Tumbleweed 1.26.9-1.1

opensuse advisories openSUSE-SU-2026:12351-1openSUSE-SU-2026:22095-1openSUSE-SU-2026:22093-1openSUSE-SU-2026:12112-1openSUSE-SU-2026:12101-1openSUSE-SU-2026:12093-1

  • go Alpine 3.24 1.26.9-r0
  • docker Alpine 3.24 29.9.0-r0

alpine advisories ALPINE-CVE-2026-56857

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-2026-56857 updated cvss 3.3

os: golang: golang: Directory traversal via Windows junction handling

  • Red Hat OpenShift Developer Tools and Services helm 3.22.0-90.el9
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat OpenShift Pipelines openshift-pipelines-client 1.15.3-11580.el8 Red Hat OpenShift Serverless kn-workflow-plugin 1.38.1-1.el9, openshift-serverless-clients 1.17.0-4.el9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat OpenShift Service Mesh 3 openshift-golang-builder-container
    affected: workaround, no fix available
  • Red Hat AMQ Clients qpid-proton 0.40.0-2.el8 Red Hat Edge Manager 1 flightctl 1.3.1-1.el10 Red Hat Enterprise Linux 9 runc, golang, podman, skopeo, buildah, go-toolset, +19 more Red Hat Enterprise Linux 10 skopeo 1.24.0-2.el10, buildah 1.45.0-2.el10, trustee 0.15.0-2.el10, golang 1.26.10-1.el10_2, trustee-guest-components 0.13.0-1.el10 Red Hat OpenShift Container Platform 4 runc, cri-o, butane, conmon, skopeo, conmon-rs, +24 more Red Hat OpenShift Container Platform 5 runc, butane, conmon-rs, cri-tools, openshift, kata-containers, +5 more
    +1 more products
    Red Hat OpenShift on AWS rosa 1.2.64-b2f7c89.el8
    affected: workaround, no fix available “Fix deferred”
  • Red Hat OpenShift Virtualization 4 openshift-golang-builder-container
    affected: workaround, no fix available
  • Red Hat Satellite 6 dynflow-utils 2.0.1-2.el10sat, rubygem-dynflow 2.0.1-2.el10sat
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Service Interconnect 2 skupper-cli 2.1.4-1.el8, skupper-router 3.5.2-1.el9
    affected: workaround, no fix available, no fix planned “Out of support scope”
  • Red Hat streams for Apache Kafka 2 golang-github-danielqsj-kafka_exporter 1.9.0-12.el9
    affected: workaround, no fix planned “Out of support scope”
show 2 more
  • Red Hat streams for Apache Kafka 3 golang-github-danielqsj-kafka_exporter 1.9.0-12.el9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Ansible Automation Orchestrator 2026 ansible-automation-platform/automation-orchestrator-rhel9-operator 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-rhel8-operator Red Hat Builds for Red Hat OpenShift openshift-builds/openshift-builds-waiters-rhel9, openshift-builds/openshift-builds-waiters-rhel10 Red Hat cert-manager Operator for Red Hat OpenShift cert-manager/jetstack-cert-manager-rhel9 Red Hat Compliance Operator compliance/openshift-compliance-operator-bundle
    +18 more products
    Red Hat Confidential Compute Attestation build-of-trustee/trustee-rhel9-operator Red Hat Cost Management Metrics Operator costmanagement/costmanagement-metrics-rhel9-operator Red Hat Cost Management On Premise costmanagement/costmanagement-ingress-rhel9 Red Hat Cryostat 4 cryostat/cryostat-storage-rhel9 Red Hat Custom Metric Autoscaler operator for Red Hat Openshift custom-metrics-autoscaler/custom-metrics-autoscaler-rhel9 Red Hat Deployment Validation Operator dvo/deployment-validation-rhel8-operator Red Hat DPU kit for NVIDIA dpu-kit-for-nvidia/dpf-hcp-provisioner-rhel10-operator Red Hat Exploit Intelligence exploit-intelligence/exploit-intelligence-operator-controller-rhel9 Red Hat External Secrets Operator for Red Hat OpenShift external-secrets-operator/external-secrets-rhel9 Red Hat Fence Agents Remediation Operator workload-availability/fence-agents-remediation-rhel8-operator Red Hat File Integrity Operator compliance/openshift-file-integrity-rhel8-operator Red Hat Gatekeeper 3 gatekeeper/gatekeeper-rhel9-operator Red Hat Helm CLI for Red Hat OpenShift helm-cli/helm-cli-rhel9 Red Hat Logging Subsystem for Red Hat OpenShift openshift-logging/eventrouter-rhel9 Red Hat Logical Volume Manager Storage lvms4/topolvm-rhel8, lvms4/topolvm-rhel9, lvms4/lvms-rhel9-operator Red Hat Machine Deletion Remediation Operator workload-availability/machine-deletion-remediation-rhel8-operator Red Hat Migration Toolkit for Applications 8 mta/mta-cli-rhel9 Red Hat Migration Toolkit for Containers rhmtc/openshift-migration-registry-rhel8
    under investigation

56 more under investigation, 5 more fixed, 17 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
yes
Technical impact
total
Assessed
30 d ago

Exploit prediction

0.55% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
OSV 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
bitnami golang
<1.26.9
>=1.27.0-0, <1.27.2
1.26.9
1.27.2
go stdlib
<1.26.9
>=1.27.0-0, <1.27.2
1.26.9
1.27.2

Affected products

  • Go standard library os
  • Go standard library internal/syscall/windows

Classification

Weakness
  • CWE-1386 Insecure Operation on Windows Junction / Mount Point

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.