CVE-2020-8561
Webhook redirect in kube-apiserver
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- High
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Webhook redirect in kube-apiserver
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.
- Record
CVE-2020-8561- CVSS 3.1
- 4.1 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:N - Weakness
- CWE-441
- Updated
- 2026-11-02
EUVDEUVD-2021-2002
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.
- Record
EUVD-2021-2002- CVSS 3.1
- 4.1 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-74j8-88mm-7496
Confused Deputy in Kubernetes
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.
- Record
GHSA-74j8-88mm-7496- CVSS 3.1
- 4.1 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:N - Weakness
- CWE-441, CWE-610
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2020-8561- CVSS 3.1
- 4.1 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:N - CVSS 2.0
- 4.0 Medium
AV:N/AC:L/Au:S/C:P/I:N/A:N - Weakness
- CWE-441, CWE-610
- Updated
- 2026-11-02
OSVAZL-89315
CVE-2020-8561 affecting package kubernetes 1.30.10-32
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.
- Record
AZL-89315- CVSS 3.1
- 4.1 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:N - Updated
- 2026-11-05
OSV
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.
- Record
CVE-2020-8561- CVSS 3.1
- 4.1 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:N - Updated
- 2026-11-02
Show 7 moreShow less
OSVDEBIAN-CVE-2020-8561
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.
- Record
DEBIAN-CVE-2020-8561- CVSS 3.1
- 4.1 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:N - Updated
- 2026-11-02
OSVGHSA-74j8-88mm-7496
Confused Deputy in Kubernetes
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.
- Record
GHSA-74j8-88mm-7496- CVSS 3.1
- 4.1 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:N - Weakness
- CWE-441, CWE-610
- Updated
- 2026-11-02
OSVUBUNTU-CVE-2020-8561
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.
- Record
UBUNTU-CVE-2020-8561- CVSS 3.1
- 4.1 Medium
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:N - Updated
- 2026-11-02
OSVopenSUSE-SU-2026:11388-1 No score
kubernetes1.33-apiserver-1.33.13-2.1 on GA media
These are all security issues fixed in the kubernetes1.33-apiserver-1.33.13-2.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2026:11388-1- Updated
- 2026-11-02
OSVopenSUSE-SU-2026:11389-1 No score
kubernetes1.34-apiserver-1.34.10-1.1 on GA media
These are all security issues fixed in the kubernetes1.34-apiserver-1.34.10-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2026:11389-1- Updated
- 2026-11-02
OSVopenSUSE-SU-2026:11390-1 No score
kubernetes1.35-apiserver-1.35.7-1.1 on GA media
These are all security issues fixed in the kubernetes1.35-apiserver-1.35.7-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2026:11390-1- Updated
- 2026-11-02
OSVopenSUSE-SU-2026:11391-1 No score
kubernetes1.36-apiserver-1.36.3-1.1 on GA media
These are all security issues fixed in the kubernetes1.36-apiserver-1.36.3-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2026:11391-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
k8s.io/kubernetesGo |
through 1.22.2 | None known |
kubernetesAzure Linux:3 |
through 1.30.10-32 | None known |
kubernetesDebian:12 |
before 1.20.5+really1.20.2-1 | 1.20.5+really1.20.2-1 |
kubernetesDebian:13 |
before 1.20.5+really1.20.2-1 | 1.20.5+really1.20.2-1 |
kubernetesDebian:14 |
before 1.20.5+really1.20.2-1 | 1.20.5+really1.20.2-1 |
kubernetes1.33openSUSE:Tumbleweed |
before 1.33.13-2.1 | 1.33.13-2.1 |
kubernetes1.34openSUSE:Tumbleweed |
before 1.34.10-1.1 | 1.34.10-1.1 |
kubernetes1.35openSUSE:Tumbleweed |
before 1.35.7-1.1 | 1.35.7-1.1 |
kubernetes1.36openSUSE:Tumbleweed |
before 1.36.3-1.1 | 1.36.3-1.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| facts | OSV | |
| affected | ||
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2020-8561 is a medium vulnerability (CVSS 4.1) in Kubernetes, published September 20, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.10%, the 81st percentile. Fixed in kubernetes 1.20.5+really1.20.2-1.