CVE-2020-8562
Bypass of Kubernetes API Server proxy TOCTOU
- Published
- Updated
- Reserved
- Assigned by
- kubernetes
Description
As mitigations to a report from 2019 and CVE-2020-8555, Kubernetes attempts to prevent proxied connections from accessing link-local or localhost networks when making user-driven connections to Services, Pods, Nodes, or StorageClass service providers. As part of this mitigation Kubernetes does a DNS name resolution check and validates that response IPs are not in the link-local (169.254.0.0/16) or localhost (127.0.0.0/8) range. Kubernetes then performs a second DNS resolution without validation for the actual connection. If a non-standard DNS server returns different non-cached responses, a user may be able to bypass the proxy IP restriction and access private networks on the control plane.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| kubernetesCNA (assigner) | 3.1 | Low2.2 | CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N |
| NVDNVD · Modified | 3.1 | Low3.1 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N |
- EPSS (exploitation in 30 days)
- 1.2% · top 32% of all CVEs (6 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Low 2.2.
Weakness
Affected products
- affected < *
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Gok8s.io/kubernetesGHSA-qh36-44jv-c8xj (opens in a new tab)
What to do
Workaround: If this issue affects your clusters’ control planes, you can use dnsmasq for name resolution and configure the min-cache-ttl and neg-ttl parameters to a low non-zero value to enforce cached replies for proxied connections
References (4)
- https://kubernetes.io/blog/2026/05/26/reconciling-unfixed-kubernetes-cves/ (opens in a new tab)x_refsource_MISC
- https://github.com/kubernetes/kubernetes/issues/101493 (opens in a new tab)x_refsource_MISCx_transferred
- https://groups.google.com/g/kubernetes-security-announce/c/-MFX60_wdOY (opens in a new tab)x_refsource_MISCx_transferred
- https://security.netapp.com/advisory/ntap-20220225-0002/ (opens in a new tab)x_refsource_CONFIRMx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-qh36-44jv-c8xj (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2020-8562)Record last updated .