CVE-2020-8557
MEDIUMCVE-2020-8557 is a medium-severity (CVSS 5.5) Uncontrolled Resource Consumption vulnerability in k8s.io/kubernetes/pkg/kubelet. O3 Security confirms whether CVE-2020-8557 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Denial of service in Kubernetes
Real-World Exposure
k8s.io/kubernetes/pkg/kubelet🐹k8s.io/kubernetes/pkg/kubelet🐹k8s.io/kubernetes/pkg/kubeletReal-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 Kubernetes kubelet component in versions 1.1-1.16.12, 1.17.0-1.17.8 and 1.18.0-1.18.5 do not account for disk usage by a pod which writes to its own /etc/hosts file. The /etc/hosts file mounted in a pod by kubelet is not included by the kubelet eviction manager when calculating ephemeral storage usage by a pod. If a pod writes a large amount of data to the /etc/hosts file, it could fill the storage space of the node and cause the node to fail.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | k8s.io/kubernetes/pkg/kubelet | ≥ 1.1.0&&< 1.16.13 | 1.16.13 |
| 🐹Go | k8s.io/kubernetes/pkg/kubelet | ≥ 1.17.0&&< 1.17.9 | 1.17.9 |
| 🐹Go | k8s.io/kubernetes/pkg/kubelet | ≥ 1.18.0&&< 1.18.6 | 1.18.6 |
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/pkg/kubelet. 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/pkg/kubelet to 1.16.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-8557 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-2020-8557 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-2020-8557. 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-2020-8557 in your dependencies?
O3 detects CVE-2020-8557 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.