# CVE-2020-8562: Bypass of Kubernetes API Server proxy TOCTOU

> Attackers can bypass Kubernetes API server proxy restrictions to access private control plane networks via DNS race conditions.

- **Severity:** Low 2.2 (`CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 Feb 2022
- **Updated:** 1 Jun 2026
- **Also known as:** AZL-89318, DEBIAN-CVE-2020-8562, GHSA-qh36-44jv-c8xj, MINI-262v-xw22-hmc4, MINI-265j-hhj6-f9f2, MINI-3367-2p29-x63f, MINI-38qj-4p67-gvvr, MINI-3h7v-pr32-vg5h, MINI-3mcq-3hm2-rmwf, MINI-46pj-27r5-xv62, MINI-4fjg-9v67-gmqg, MINI-4v2h-wg3x-mp3h, MINI-522g-45r4-85mm, MINI-532c-64f9-r325, MINI-5hmw-v26j-q6gc, MINI-5q96-wgfg-7x5r, MINI-5r53-6xmg-v77w, MINI-627v-wq6c-hj23, MINI-63g8-vrpg-gvrx, MINI-689w-955v-2j3x, MINI-69fv-fwqj-qhv5, MINI-6vg2-5cq2-phxx, MINI-6xw2-r696-6fg7, MINI-84pv-5cfp-q25r, MINI-89p3-7x5p-4f6j, MINI-8j85-pr4m-c3cv, MINI-8p9c-883c-whqc, MINI-8pgh-753m-x557, MINI-9272-8gxg-gx95, MINI-f47m-wg9c-hm48, MINI-f8mv-9jh5-xrfv, MINI-fxmm-9xrv-q7mw, MINI-h49x-wqwm-xm34, MINI-hf9f-gq7w-vw4g, MINI-hgrm-46cw-8hq5, MINI-j55j-j8m6-cqgg, MINI-j823-5r7w-3898, MINI-j9cg-pm72-r8cx, MINI-jf85-mv26-cg88, MINI-mwjw-jp43-4fq4, MINI-pfcj-qhq2-wr7m, MINI-pp7j-5cm7-p2v4, MINI-pxr3-gcgf-62f7, MINI-qf6j-69gv-rr5h, MINI-qfch-rfwm-28jf, MINI-qvfc-2c42-h35h, MINI-v538-wv7g-vqf2, MINI-v6r6-7gj9-wjgv, MINI-vhqc-xhxf-9j4r, MINI-vrpw-46q4-29pm, MINI-wg7r-mx9m-hhfr, MINI-xcqh-g97p-98h2, MINI-xfw6-cj64-cmfq, MINI-xqg2-976r-49mh, MINI-xrjf-qq5v-pwqm

## What is CVE-2020-8562?

CVE-2020-8562 is a low-severity server-side request forgery vulnerability in Kubernetes Kubernetes, published on 1 Feb 2022. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

As mitigations to a report from 2019 and CVE-2020-8555, Kubernetes attempts to prevent proxied connections from accessing link-local or localhost networks when making user-driven connections to Services, Pods, Nodes, or StorageClass service providers. As part of this mitigation Kubernetes does a DNS name resolution check and validates that response IPs are not in the link-local (169.254.0.0/16) or localhost (127.0.0.0/8) range. Kubernetes then performs a second DNS resolution without validation for the actual connection. If a non-standard DNS server returns different non-cached responses, a user may be able to bypass the proxy IP restriction and access private networks on the control plane.

Weakness: CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition)

## Which versions are affected by CVE-2020-8562?

8 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 to 1.18.19 | None |
| `k8s.io/kubernetes` | Go | All versions to 1.18.19 | None |
| `k8s.io/kubernetes` | Go | From 1.19.0 to 1.19.11 | None |
| `k8s.io/kubernetes` | Go | From 1.19.0 to 1.19.11 | None |
| `k8s.io/kubernetes` | Go | From 1.20.0 to 1.20.7 | None |
| `k8s.io/kubernetes` | Go | From 1.20.0 to 1.20.7 | None |
| `k8s.io/kubernetes` | Go | From 1.21.0 to 1.21.1 | None |
| `k8s.io/kubernetes` | Go | From 1.21.0 to 1.21.1 | None |

Products: Kubernetes Kubernetes.

## How do I fix CVE-2020-8562?

Apply the vendor's patch.

## Is CVE-2020-8562 being exploited?

There is no known exploitation of CVE-2020-8562 in the wild and no public exploit code.

## 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-2020-8562 and fix it if it is affected.

What it is: CVE-2020-8562 is a low-severity server-side request forgery vulnerability in Kubernetes Kubernetes, published on 1 Feb 2022. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-8562 in the wild and no public exploit code.

Affected packages and fixed versions:
- k8s.io/kubernetes (Go): affected all versions up to 1.18.19; no fix listed
- k8s.io/kubernetes (Go): affected all versions up to 1.18.19; no fix listed
- k8s.io/kubernetes (Go): affected from 1.19.0 up to 1.19.11; no fix listed
- k8s.io/kubernetes (Go): affected from 1.19.0 up to 1.19.11; no fix listed
- k8s.io/kubernetes (Go): affected from 1.20.0 up to 1.20.7; no fix listed
- k8s.io/kubernetes (Go): affected from 1.20.0 up to 1.20.7; no fix listed
- k8s.io/kubernetes (Go): affected from 1.21.0 up to 1.21.1; no fix listed
- k8s.io/kubernetes (Go): affected from 1.21.0 up to 1.21.1; no fix listed

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-2020-8562/ (Markdown: https://insights.sbomify.com/CVE-2020-8562/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-8562
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-8562
- OSV: https://osv.dev/vulnerability/CVE-2020-8562

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-8562/
Summaries are generated and may contain mistakes; the official description above is the record.