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MEDIUM severity

CVE-2020-8557 — kubelet

MEDIUMFix: kubernetes/kubernetes#92921

CVE-2020-8557 is a medium-severity (CVSS 5.5) Uncontrolled Resource Consumption vulnerability in k8s.io/kubernetes/pkg/kubelet. A fix is available for k8s.io/kubernetes/pkg/kubelet — see the affected versions and patch details below.

Denial of service in Kubernetes

Also known asGHSA-55qj-gj3x-jq9rGO-2024-2753
Published
Updated
Affected
3 pkgs
Patched
3 / 3
Exploits
None indexed
Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs38th percentile — riskier than 38% of all scored CVEsHighest risk
0.00%0.33%0.67%1.00%0.1%0.4%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/pkg/kubelet🐹k8s.io/kubernetes/pkg/kubelet🐹k8s.io/kubernetes/pkg/kubelet

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

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

3 total 3 fixed
EcosystemPackageVulnerable rangeFix
🐹Gok8s.io/kubernetes/pkg/kubelet≥ 1.1.0&&< 1.16.131.16.13go get k8s.io/kubernetes/pkg/kubelet@v1.16.13
🐹Gok8s.io/kubernetes/pkg/kubelet≥ 1.17.0&&< 1.17.91.17.9go get k8s.io/kubernetes/pkg/kubelet@v1.17.9
🐹Gok8s.io/kubernetes/pkg/kubelet≥ 1.18.0&&< 1.18.61.18.6go get k8s.io/kubernetes/pkg/kubelet@v1.18.6

Affected Products

1 product · 3 configurations
Application
kuberneteskubernetes
≥ 1.18.0 && < 1.18.6
range

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/pkg/kubelet, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. 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.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

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

In OpenShift Container Platform (OCP) there is LocalStorageCapacityIsolation feature gate functionality which prevents a denial of service (DoS) attack on the node by writing to the ephemeral storage.This feature is disabled by default in OCP 3.11 and can be enabled as per [1]. Even with enabled…

Workaround published by Red Hat
On OpenShift Container Platform (OCP) 3.11 and 4.x it's possible to set the allowPrivilegeEscalation Security Context Constraint to 'false' to prevent this. Note that this is set to 'true' by default, and setting it to false will prevent certain binaries which require setuid to stop working. On OCP 3.11 for example the 'ping' command will no longer work [1]. On OCP 4.x and later the 'ping' command will work with allowPrivilegeEscalation set to False, but other setuid binaries will not work. [1] https://docs.openshift.com/container-platform/3.11/release_notes/ocp_3_11_release_notes.html
Source: Red Hat security advisory for CVE-2020-8557 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat OpenShift Container Platform 3.11atomic-openshift-0:3.11.542-1.git.0.f2fd300.el7RHSA-2021:3915
Red Hat OpenShift Container Platform 4.3openshift4/ose-hyperkube:v4.3.37-202009151447.p0RHSA-2020:3809
Red Hat OpenShift Container Platform 4.3openshift-0:4.3.37-202009120213.p0.git.0.dffefe4.el8RHSA-2020:3808
Red Hat OpenShift Container Platform 4.4openshift-0:4.4.0-202008250319.p0.git.0.d653415.el7RHSA-2020:3579
Red Hat OpenShift Container Platform 4.4openshift4/ose-hyperkube:v4.4.0-202008250319.p0RHSA-2020:3580
Red Hat OpenShift Container Platform 4.5openshift-0:4.5.0-202008130146.p0.git.0.aaf1d57.el7RHSA-2020:3519
Red Hat OpenShift Container Platform 4.5openshift4/ose-hyperkube:v4.5.0-202008130146.p0RHSA-2020:3520
Red Hat OpenShift Container Platform 4.6openshift4/ose-aws-ebs-csi-driver-rhel8:v4.6.0-202010061132.p0RHBA-2020:4196

Frequently Asked Questions

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.
O3 Security · Impact-Aware SCA

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CVE-2020-8557: kubelet — Fixed in 1.16.13