CVE-2020-8558 — kubernetes
HIGHCVE-2020-8558 is a high-severity (CVSS 8.8) CWE-420 vulnerability in k8s.io/kubernetes. 6 public exploit references exist, 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
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2020-8558 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
k8s.io/kubernetes🐹k8s.io/kubernetes🐹k8s.io/kubernetesReal-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
The Kubelet and kube-proxy components in versions 1.1.0-1.16.10, 1.17.0-1.17.6, and 1.18.0-1.18.3 were found to contain a security issue 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. Such a service is generally thought to be reachable only by other processes on the same host, but due to this defeect, could be reachable by other hosts on the same LAN as the node, or by containers running on the same node as the service.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | k8s.io/kubernetes | ≥ 1.18.0&&< 1.18.4 | 1.18.4go get k8s.io/kubernetes@v1.18.4 |
| 🐹Go | k8s.io/kubernetes | ≥ 1.17.0&&< 1.17.7 | 1.17.7go get k8s.io/kubernetes@v1.17.7 |
| 🐹Go | k8s.io/kubernetes | all versions | 1.16.11go get k8s.io/kubernetes@v1.16.11 |
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-…
The Kubelet and kube-proxy components in versions 1.1.0-1.16.10, 1.17.0-…
The Kubelet and kube-proxy components in versions 1.1.0-1.16.10, 1.17.0-…
The Kubelet and kube-proxy components in versions 1.1.0-1.16.10, 1.17.0-…
Detection & mitigation playbook
Open-source dependencyDetect
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.
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.
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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2020-8558 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2020-8558. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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.
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.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat OpenShift Container Platform 3.11 | atomic-openshift-0:3.11.248-1.git.0.92ee8ac.el7 | RHSA-2020:2992 |
| Red Hat OpenShift Container Platform 4.3 | openshift-0:4.3.31-202007280738.p0.git.0.9884401.el7 | RHSA-2020:3183 |
| Red Hat OpenShift Container Platform 4.3 | openshift4/ose-hyperkube:v4.3.31-202007272153.p0 | RHSA-2020:3184 |
| Red Hat OpenShift Container Platform 4.4 | openshift4/ose-hyperkube:v4.4.0-202007120152.p0 | RHSA-2020:2926 |
| Red Hat OpenShift Container Platform 4.4 | openshift-0:4.4.0-202007090832.p0.git.0.bc32fb1.el7 | RHSA-2020:2927 |
| Red Hat OpenShift Container Platform 4.5 | openshift4/ose-hyperkube:v4.5.0-202007100518.p0 | RHSA-2020:2412 |
| Red Hat OpenShift Container Platform 4.5 | openshift-0:4.5.0-202007012112.p0.git.0.582d7fc.el7 | RHSA-2020:2413 |
Frequently Asked Questions
Is CVE-2020-8558 in your dependencies?
O3 Security finds CVE-2020-8558 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.