CVE-2020-8561

Name: CVE-2020-8561
Creator: NVD / NIST
Published: 2021-09-20T17:15:08.187+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.1/10EPSS 1.95%

Last modified Jun 17, 2026

CVE-2020-8561 is a medium-severity vulnerability rated 4.1/10 on the CVSS scale. A security issue was discovered in Kubernetes where actors that control the responses of MutatingWebhookConfiguration or ValidatingWebhookConfiguration requests are able to redirect kube-apiserver requests to private networks of the apiserver. If that user can view kube-apiserver logs when the log level is set to 10, they can view the redirected responses and headers in the logs.. EPSS estimates a 1.95% chance of exploitation in the next 30 days.

Description

A security issue was discovered in Kubernetes where actors that control the responses of MutatingWebhookConfiguration or ValidatingWebhookConfiguration requests are able to redirect kube-apiserver requests to private networks of the apiserver. If that user can view kube-apiserver logs when the log level is set to 10, they can view the redirected responses and headers in the logs.

Metrics

CVSS 3.1

4.1/10

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

EPSS Probability

1.95%

77.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Kubernetes	Kubernetes	1.20.11
Kubernetes	Kubernetes	1.21.5
Kubernetes	Kubernetes	1.22.2

References

https://github.com/kubernetes/kubernetes/issues/104720Mitigation, Third Party Advisory
https://groups.google.com/g/kubernetes-security-announce/c/RV2IhwcrQsYMailing List, Mitigation
https://kubernetes.io/blog/2026/05/26/reconciling-unfixed-kubernetes-cves/
https://security.netapp.com/advisory/ntap-20211014-0002/Third Party Advisory
https://github.com/kubernetes/kubernetes/issues/104720Mitigation, Third Party Advisory
https://groups.google.com/g/kubernetes-security-announce/c/RV2IhwcrQsYMailing List, Mitigation
https://security.netapp.com/advisory/ntap-20211014-0002/Third Party Advisory

Timeline

Published: Sep 20, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-8561?

How severe is CVE-2020-8561?

CVE-2020-8561 has a CVSS score of 4.1/10 (MEDIUM severity). The EPSS model estimates a 1.95% probability of exploitation in the next 30 days.

How do I fix CVE-2020-8561?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-8561?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST