Improper Authentication in Kubernetes

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.8 · CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2020-8558: 3.42% estimated exploitation activity in the next 30 days; percentile 88.91 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

15 Feb 2022, 01:57 UTC

Last modified by the source

30 Jan 2023, 05:00 UTC

Source last checked

26 Oct 2026, 14:54 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-wqv3-8cm6-h6wg

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2020-8558

Advisory: Improper Authentication in Kubernetes
IDs: CVE-2020-8558, GHSA-wqv3-8cm6-h6wg
Record: https://patchnext.com/advisories/cve-2020-8558 (revision 1, source checked 26 Oct 2026, 14:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: k8s.io/kubernetes 1.18.4, 1.17.7, 1.16.11. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go k8s.io/kubernetes: affected >= 1.18.0, < 1.18.4; >= 1.17.0, < 1.17.7; < 1.16.11; fixed in 1.17.7, 1.16.11, 1.18.4

## Suggested inspection (read-only)
- Go k8s.io/kubernetes: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on k8s.io/kubernetes.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-wqv3-8cm6-h6wg (GitHub-reviewed advisory GHSA-wqv3-8cm6-h6wg lists affected ranges: Go k8s.io/kubernetes >=1.18.0 =1.17.0 =0 <1.16.11)

Commands are suggestions: review each one before running it.