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HIGH severity

CVE-2020-8558 — kubernetes

HIGH

CVE-2020-8558 is a high-severity (CVSS 8.8) CWE-420 vulnerability in k8s.io/kubernetes. 6 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for k8s.io/kubernetes — see the affected versions and patch details below.

Improper Authentication in Kubernetes

Also known asGHSA-wqv3-8cm6-h6wgGO-2022-0885
Published
Updated
Affected
3 pkgs
Patched
3 / 3
Exploits
6 known
Exploitation data as of Nov 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
3.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs89th percentile — riskier than 89% of all scored CVEsHighest risk
0.00%8.39%16.8%25.2%20.1%3.4%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

3 pkgs affected
🐹k8s.io/kubernetes🐹k8s.io/kubernetes🐹k8s.io/kubernetes

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

A security issue was discovered in the Kubelet and kube-proxy components of Kubernetes which allows adjacent hosts to reach TCP and UDP services bound to 127.0.0.1 running on the node or in the node's network namespace. For example, if a cluster administrator runs a TCP service on a node that listens on 127.0.0.1:1234, because of this bug, that service would be potentially reachable by other hosts on the same LAN as the node, or by containers running on the same node as the service. If the example service on port 1234 required no additional authentication (because it assumed that only other localhost processes could reach it), then it could be vulnerable to attacks that make use of this bug.

Affected Packages

3 total 3 fixed
EcosystemPackageVulnerable rangeFix
🐹Gok8s.io/kubernetes≥ 1.18.0&&< 1.18.41.18.4go get k8s.io/kubernetes@v1.18.4
🐹Gok8s.io/kubernetes≥ 1.17.0&&< 1.17.71.17.7go get k8s.io/kubernetes@v1.17.7
🐹Gok8s.io/kubernetesall versions1.16.11go get k8s.io/kubernetes@v1.16.11

Affected Products

1 product · 3 configurations
Application
kuberneteskubernetes
≥ 1.18.0 && ≤ 1.18.3
range
Exploits & PoCs
6

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

The Kubelet and kube-proxy components in versions 1.1.0-1.16.10, 1.17.0-…

github.comNVDAug 2020

Report on groups.google.com

groups.google.comNVDAug 2020

Report on github.com

github.comGithubJul 2020

Report on github.com

github.comGithubJul 2020

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for k8s.io/kubernetes, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update k8s.io/kubernetes to 1.18.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-8558 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

OpenShift Container Platform does not expose the API server on a localhost port without authentication. The only service exposed on a localhost port not protected by authentication is Metrics, which exposes some cluster metadata.

ProductFixed inAdvisory
Red Hat OpenShift Container Platform 3.11atomic-openshift-0:3.11.248-1.git.0.92ee8ac.el7RHSA-2020:2992
Red Hat OpenShift Container Platform 4.3openshift-0:4.3.31-202007280738.p0.git.0.9884401.el7RHSA-2020:3183
Red Hat OpenShift Container Platform 4.3openshift4/ose-hyperkube:v4.3.31-202007272153.p0RHSA-2020:3184
Red Hat OpenShift Container Platform 4.4openshift4/ose-hyperkube:v4.4.0-202007120152.p0RHSA-2020:2926
Red Hat OpenShift Container Platform 4.4openshift-0:4.4.0-202007090832.p0.git.0.bc32fb1.el7RHSA-2020:2927
Red Hat OpenShift Container Platform 4.5openshift4/ose-hyperkube:v4.5.0-202007100518.p0RHSA-2020:2412
Red Hat OpenShift Container Platform 4.5openshift-0:4.5.0-202007012112.p0.git.0.582d7fc.el7RHSA-2020:2413
Red Hat OpenShift Container Platform 4.6openshift4/ose-aws-ebs-csi-driver-rhel8:v4.6.0-202010061132.p0RHBA-2020:4196

Frequently Asked Questions

A security issue was discovered in the Kubelet and kube-proxy components of Kubernetes which allows adjacent hosts to reach TCP and UDP services bound to 127.0.0.1 running on the node or in the node's network namespace. For example, if a cluster administrator runs a TCP service on a node that listens on 127.0.0.1:1234, because of this bug, that service would be potentially reachable by other hosts on the same LAN as the node, or by containers running on the same node as the service. If the example service on port 1234 required no additional authentication (because it assumed that only other lo
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CVE-2020-8558: kubernetes — Fixed in 1.18.4