Vulnerability · Published Sep 20, 2021 · Assigned by kubernetes
CVE-2020-8561Webhook redirect in kube-apiserver
Medium 4.1
In plain English
A medium-severity security flaw in Kubernetes from Kubernetes. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 2.1% (higher than 82% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | kubernetes | 1.20.5+really1.20.2-1 | DEBIAN-CVE-2020-8561 |
| Debian:13 | kubernetes | 1.20.5+really1.20.2-1 | DEBIAN-CVE-2020-8561 |
| Debian:14 | kubernetes | 1.20.5+really1.20.2-1 | DEBIAN-CVE-2020-8561 |
| Go | k8s.io/kubernetes | no fix listed | GHSA-74j8-88mm-7496 |
| Ubuntu:22.04:LTS | kubernetes | no fix listed | UBUNTU-CVE-2020-8561 |
| Ubuntu:24.04:LTS | kubernetes | no fix listed | UBUNTU-CVE-2020-8561 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Kubernetes | Kubernetes | 0 – before * |
Weakness: CWE-441 · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:N
References
- https://kubernetes.io/blog/2026/05/26/reconciling-unfixed-kubernetes-cves/ x_refsource_MISC
- https://groups.google.com/g/kubernetes-security-announce/c/RV2IhwcrQsY x_refsource_MISC
- https://github.com/kubernetes/kubernetes/issues/104720 x_refsource_MISC
- https://security.netapp.com/advisory/ntap-20211014-0002/ x_refsource_CONFIRM