CVE-2020-8561: Webhook redirect in kube-apiserver

Published Sep 20, 2021
·
Updated

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.

Affected Software

4 affected componentsFixes available
Kubernetes kubernetes=1.20.11
Kubernetes kubernetes=1.21.5
Kubernetes kubernetes=1.22.2
Microsoft cm1 kubernetes 1.22.6-1

Event History

Sep 20, 2021
CVE Published
via MITRE·05:05 PM
Data Sourced
via MITRE·05:05 PM
DescriptionSeverityWeakness
Data Sourced
via NVD·05:15 PM
DescriptionSeverityWeaknessAffected Software
Oct 2, 2025
Data Sourced
via Microsoft·06:11 AM
DescriptionSeverityWeakness
Data Sourced
via Microsoft·06:11 AM
Affected Software
Updated
via Microsoft·06:11 AM
DescriptionSeverity
Free Weekly Intel

Don't miss critical vulnerabilities

Join thousands of security professionals who receive our weekly digest of trending CVEs, zero-days, and exploited vulnerabilities.

No spam. Unsubscribe anytime.

Frequently Asked Questions

1

What is CVE-2020-8561?

CVE-2020-8561 is a security issue discovered in Kubernetes that allows actors to redirect kube-apiserver requests to private networks.

2

What is the severity of CVE-2020-8561?

The severity of CVE-2020-8561 is medium with a CVSS score of 4.1.

3

Which software versions are affected by CVE-2020-8561?

Kubernetes versions 1.20.11, 1.21.5, and 1.22.2 are affected by CVE-2020-8561.

4

How can actors exploit CVE-2020-8561?

Actors can exploit CVE-2020-8561 by controlling the responses of MutatingWebhookConfiguration or ValidatingWebhookConfiguration requests to redirect kube-apiserver requests.

5

How can I fix CVE-2020-8561?

To fix CVE-2020-8561, update your Kubernetes version to a patched version as mentioned in the official references.

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203