CVE-2020-8558
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. O3 Security confirms whether CVE-2020-8558 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Improper Authentication in Kubernetes
Blast Radius
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 | 1.18.4 |
| 🐹Go | k8s.io/kubernetes | ≥ 1.17.0&&< 1.17.7 | 1.17.7 |
| 🐹Go | k8s.io/kubernetes | all versions | 1.16.11 |
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. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
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 pinpoints whether CVE-2020-8558 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
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.
Frequently Asked Questions
Is CVE-2020-8558 in your dependencies?
O3 detects CVE-2020-8558 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.