CVE-2020-8561
published 2021-09-20CVE-2020-8561: A security issue was discovered in Kubernetes where actors that control the responses of MutatingWebhookConfiguration or ValidatingWebhookConfiguration…
PriorityP420medium4.1CVSS 3.1
AVNACLPRHUINSCCLINAN
EPSS
1.95%
77.8th percentile
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
11 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | kubernetes | < kubernetes 1.20.5+really1.20.2-1 (bookworm) | kubernetes 1.20.5+really1.20.2-1 (bookworm) |
| k8s.io | kubernetes | 0 – 1.22.2 | — |
| kubernetes | kubernetes | < * | * |
| kubernetes | kubernetes | — | — |
| kubernetes | kubernetes | — | — |
| kubernetes | kubernetes | — | — |
| kubernetes | kubernetes | >= 0 < 1.20.5+really1.20.2-1 | 1.20.5+really1.20.2-1 |
| kubernetes | kubernetes | >= 0 < 1.20.5+really1.20.2-1 | 1.20.5+really1.20.2-1 |
| kubernetes | kubernetes | >= 0 < 1.20.5+really1.20.2-1 | 1.20.5+really1.20.2-1 |
| kubernetes | kubernetes | >= 0 < 1.20.5+really1.20.2-1 | 1.20.5+really1.20.2-1 |
| msrc | cm1_kubernetes_1.22.6-1_on_cbl_mariner_1.0 | — | — |
CVSS provenance
nvdv3.14.1MEDIUMCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:N
nvdv2.04.0MEDIUMAV:N/AC:L/Au:S/C:P/I:N/A:N
osv4.1MEDIUM
vendor_debian4.1MEDIUM
vendor_msrc4.1MEDIUM
vendor_redhat4.1MEDIUM
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OSV
Confused Deputy in Kubernetes
osv·2021-09-21
CVE-2020-8561 [MEDIUM] Confused Deputy in Kubernetes
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.
GHSA
Confused Deputy in Kubernetes
ghsa·2021-09-21
CVE-2020-8561 [MEDIUM] CWE-441 Confused Deputy in Kubernetes
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.
OSV
CVE-2020-8561: A security issue was discovered in Kubernetes where actors that control the responses of MutatingWebhookConfiguration or ValidatingWebhookConfiguratio
osv·2021-09-20·CVSS 4.1
CVE-2020-8561 [MEDIUM] CVE-2020-8561: A security issue was discovered in Kubernetes where actors that control the responses of MutatingWebhookConfiguration or ValidatingWebhookConfiguratio
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.
Red Hat
kubernetes: Webhook redirect in kube-apiserver
vendor_redhat·2021-09-15·CVSS 4.1
CVE-2020-8561 [MEDIUM] CWE-601 kubernetes: Webhook redirect in kube-apiserver
kubernetes: 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.
A flaw was found in Kubernetes. This flaw allows an actor that controls the responses of the MutatingWebhookConfiguration or the ValidatingWebhookConfiguration requests to redirect kube-apiserver requests to the private network 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 head
Microsoft
Webhook redirect in kube-apiserver
vendor_msrc·2021-09-14·CVSS 4.1
CVE-2020-8561 [MEDIUM] CWE-441 Webhook redirect in kube-apiserver
Webhook redirect in kube-apiserver
FAQ: Is Azure Linux the only Microsoft product that includes this open-source library and is therefore potentially affected by this vulnerability?
One of the main benefits to our customers who choose to use the Azure Linux distro is the commitment to keep it up to date with the most recent and most secure versions of the open source libraries with which the distro is composed. Microsoft is committed to transparency in this work which is why we began publishing CSAF/VEX in October 2025. See this blog post for more information. If impact to additional products is identified, we will update the CVE to reflect this.
Mariner: Mariner
kubernetes: kubernetes
Customer Action Required: Yes
Remediation: CBL-Mariner Releases
Reference: https://learn.microsoft.
Debian
CVE-2020-8561: kubernetes - A security issue was discovered in Kubernetes where actors that control the resp...
vendor_debian·2020·CVSS 4.1
CVE-2020-8561 [MEDIUM] CVE-2020-8561: kubernetes - A security issue was discovered in Kubernetes where actors that control the resp...
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.
Scope: local
bookworm: resolved (fixed in 1.20.5+really1.20.2-1)
bullseye: resolved (fixed in 1.20.5+really1.20.2-1)
forky: resolved (fixed in 1.20.5+really1.20.2-1)
sid: resolved (fixed in 1.20.5+really1.20.2-1)
trixie: resolved (fixed in 1.20.5+really1.20.2-1)
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
https://github.com/kubernetes/kubernetes/issues/104720https://groups.google.com/g/kubernetes-security-announce/c/RV2IhwcrQsYhttps://kubernetes.io/blog/2026/05/26/reconciling-unfixed-kubernetes-cves/https://security.netapp.com/advisory/ntap-20211014-0002/https://github.com/kubernetes/kubernetes/issues/104720https://groups.google.com/g/kubernetes-security-announce/c/RV2IhwcrQsYhttps://security.netapp.com/advisory/ntap-20211014-0002/
2021-09-20
Published