Vulnerability in Kubernetes
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.021 (81.0th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 81st percentile — 81.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.021 · newest: 0.021 · change: 0.000
Affected products
- Kubernetes — versions 1.21.5, next of 1.21.5, next of 1.22.2
Weakness classification (CWE)
Public proof-of-concept exploits
References
- groups.google.com/g/kubernetes-security-announce/c/RV2IhwcrQsY (Mailing List, Mitigation)
- github.com/kubernetes/kubernetes/issues/104720 (Third Party Advisory, Mitigation)
- security.netapp.com/advisory/ntap-20211014-0002/ (Third Party Advisory)
- kubernetes.io/blog/2026/05/26/reconciling-unfixed-kubernetes-cves/
Frequently asked questions
- What is CVE-2020-8561?
- CVE-2020-8561 is a medium-severity vulnerability in Kubernetes, classified under Unintended Proxy or Intermediary (Confused Deputy). CVSS score: 4.1/10. Published 2021-09-20.
- How severe is CVE-2020-8561?
- Medium severity. CVSS v3 base score is 4.1 out of 10.
- Is CVE-2020-8561 known to be exploited?
- 3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.