# CVE-2020-8558: Kubernetes node setting allows for neighboring hosts to bypass localhost boundary


- **Severity:** Medium 5.4 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 27 Jul 2020
- **Updated:** 16 Sep 2024
- **Also known as:** CLEANSTART-2025-WT23235, DEBIAN-CVE-2020-8558, GHSA-wqv3-8cm6-h6wg, GO-2022-0885, RHSA-2020:3183

## What is CVE-2020-8558?

CVE-2020-8558 is a medium-severity vulnerability in Kubernetes Kubernetes, published on 27 Jul 2020. 

### Official 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.

Weakness: CWE-420 (Unprotected Alternate Channel)

## Which versions are affected by CVE-2020-8558?

7 open source packages ship an affected version, including k8s.io/kubernetes. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `k8s.io/kubernetes` | Go | All versions | 1.16.11, 1.17.7, 1.18.4 |
| `k8s.io/kubernetes` | Go | All versions | 1.16.11 |
| `k8s.io/kubernetes` | Go | All versions | 1.16.11 |
| `k8s.io/kubernetes` | Go | From 1.17.0 | 1.17.7 |
| `k8s.io/kubernetes` | Go | From 1.17.0 | 1.17.7 |
| `k8s.io/kubernetes` | Go | From 1.18.0 | 1.18.4 |
| `k8s.io/kubernetes` | Go | From 1.18.0 | 1.18.4 |
| `openshift` | Red Hat:openshift:4.3::el7 | All versions | 0:4.3.31-202007280738.p0.git.0.9884401.el7 |
| `openshift-hyperkube` | Red Hat:openshift:4.3::el7 | All versions | 0:4.3.31-202007280738.p0.git.0.9884401.el7 |
| `openshift` | Red Hat:openshift:4.3::el8 | All versions | 0:4.3.31-202007280738.p0.git.0.9884401.el8 |
| `openshift-hyperkube` | Red Hat:openshift:4.3::el8 | All versions | 0:4.3.31-202007280738.p0.git.0.9884401.el8 |

Products: Kubernetes Kubernetes.

## How do I fix CVE-2020-8558?

Upgrade k8s.io/kubernetes to a fixed version for your release line: 1.16.11, 1.17.7 or 1.18.4.

## Is CVE-2020-8558 being exploited?

There is no known exploitation of CVE-2020-8558 in the wild and no public exploit code.

Public exploit code:

- Information about Kubernetes CVE-2020-8558, including proof of concept exploit. (github_poc): https://github.com/tabbysable/POC-2020-8558
- Crafting raw TCP/IP packets to send to poorly configured Kubernetes servers - CVE-2020-8558 PoC (github_poc): https://github.com/rhysemmas/martian-packets

## Other vulnerabilities in Kubernetes Kubernetes

- [CVE-2018-1002105](https://insights.sbomify.com/CVE-2018-1002105/): Privilege Escalation in Kubernetes (critical 9.8)
- [CVE-2017-1000056](https://insights.sbomify.com/CVE-2017-1000056/): Kubernetes Privilege Escalation (critical 9.8)
- [CVE-2016-1906](https://insights.sbomify.com/CVE-2016-1906/): Authorization bypass in Openshift (critical 9.8)
- [CVE-2023-3676](https://insights.sbomify.com/CVE-2023-3676/): Kubernetes - Windows nodes - Insufficient input sanitization leads to privilege escalation (high 8.8)
- [CVE-2023-3955](https://insights.sbomify.com/CVE-2023-3955/): Kubernetes - Windows nodes - Insufficient input sanitization leads to privilege escalation (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-8558 and fix it if it is affected.

What it is: CVE-2020-8558 is a medium-severity vulnerability in Kubernetes Kubernetes, published on 27 Jul 2020. 
Exploitation: There is no known exploitation of CVE-2020-8558 in the wild and no public exploit code.

Affected packages and fixed versions:
- k8s.io/kubernetes (Go): affected all versions; fixed in 1.16.11, 1.17.7, 1.18.4
- k8s.io/kubernetes (Go): affected all versions; fixed in 1.16.11
- k8s.io/kubernetes (Go): affected all versions; fixed in 1.16.11
- k8s.io/kubernetes (Go): affected from 1.17.0; fixed in 1.17.7
- k8s.io/kubernetes (Go): affected from 1.17.0; fixed in 1.17.7
- k8s.io/kubernetes (Go): affected from 1.18.0; fixed in 1.18.4
- k8s.io/kubernetes (Go): affected from 1.18.0; fixed in 1.18.4

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2020-8558/ (Markdown: https://insights.sbomify.com/CVE-2020-8558/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-8558
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-8558
- OSV: https://osv.dev/vulnerability/CVE-2020-8558

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-8558/
Summaries are generated and may contain mistakes; the official description above is the record.