# CVE-2020-8562: Kubernetes proxy IP restriction bypass via DNS TOCTOU

Source: https://junglewise.ai/threats/cve-2020-8562-kubernetes-proxy-ip-restriction-bypass-via-dns-toctou  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2022-02-02. Updated: 2026-06-09  
License: CC BY 4.0 with a link back

CVE-2020-8562 · Severity: low · CVSS 3.1 · Published 2022-02-02

Kubernetes is an open-source system for automating deployment, scaling, and management of containerized applications. A vulnerability exists where the system's security checks can be bypassed, potentially allowing an attacker to access private internal networks on the control plane. This could lead to unauthorized access to sensitive internal services or data that should otherwise be restricted.

Technologies: [k8s.io/kubernetes (Go)](https://junglewise.ai/threats/technologies/k8s-io-kubernetes), [Kubernetes](https://junglewise.ai/threats/technologies/kubernetes). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Kubernetes](https://junglewise.ai/threats/vendors/kubernetes).

## Quick answers

**Is CVE-2020-8562 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2020-8562 being exploited in the wild.

**How severe is CVE-2020-8562?** Low severity, with a CVSS score of 3.1, published 2 February 2022.

**Which products and versions are affected?** k8s.io/kubernetes (Go) SEMVER:introduced=0, SEMVER:introduced=1.21.0,last_affected=1.21.1; Kubernetes <= 1.18.19, 1.19.0-1.19.11, 1.20.0-1.20.7, 1.21.0-1.21.1.

**Is there a fix for CVE-2020-8562?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2020-8562 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2020-8562?** Check whether you run k8s.io/kubernetes (Go) or Kubernetes at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A Time-of-Check Time-of-Use (TOCTOU) vulnerability exists in Kubernetes' proxy IP restriction logic. When making user-driven connections to Services, Pods, Nodes, or StorageClass providers, Kubernetes performs an initial DNS resolution to validate that the resulting IP is not in the link-local (169.254.0.0/16) or localhost (127.0.0.0/8) range. However, it then performs a second, unvalidated DNS resolution for the actual connection. An attacker using a malicious DNS server can return a safe IP for the first check and a restricted IP for the second, bypassing the mitigation. This requires network access and low privileges. At the time of advisory, no fix was available.

## Affected products

- Kubernetes Kubernetes <= 1.18.19, 1.19.0-1.19.11, 1.20.0-1.20.7, 1.21.0-1.21.1

## Identifiers

- CVE-2020-8562
- GHSA-qh36-44jv-c8xj
- GO-2022-0617

## Timeline

- 2022-02-01: disclosed: NVD publication date
- 2022-02-02: advisory: GitHub Advisory published

## References

- [https://api.github.com/users/enj](https://api.github.com/users/enj)
- [https://github.com/enj](https://github.com/enj)
- [https://api.github.com/users/enj/gists%7B/gist_id%7D](https://api.github.com/users/enj/gists%7B/gist_id%7D)
- [https://api.github.com/users/enj/repos](https://api.github.com/users/enj/repos)
- [https://avatars.githubusercontent.com/u/7001223?v=4](https://avatars.githubusercontent.com/u/7001223?v=4)
- [https://api.github.com/users/enj/events%7B/privacy%7D](https://api.github.com/users/enj/events%7B/privacy%7D)

## Related threats

- [kube-controller-manager is vulnerable to half-blind Server Side Request Forgery through in-tree Portworx StorageClass](https://junglewise.ai/threats/cve-2025-13281-kube-controller-manager-is-vulnerable-to-half-blind-server-side)
- [A SQL Injection vulnerability exists in Esri ArcGIS Server versions 11.3, 11.4 and 11.5 on Windows, Linux and…](https://junglewise.ai/threats/cve-2025-57870-a-sql-injection-vulnerability-exists-in-esri-arcgis-server)
- [GO-2025-3915 - Kubernetes Nodes can delete themselves by adding an OwnerReference in k8s.io/kubernetes](https://junglewise.ai/threats/cve-2025-5187-kubernetes-nodes-can-delete-themselves-by-adding-an-ownerreference)
- [GO-2025-3774 - Kubernetes allows nodes to bypass dynamic resource allocation authorization checks in k8s.io/kubernetes](https://junglewise.ai/threats/cve-2025-4563-kubernetes-allows-nodes-to-bypass-dynamic-resource-allocation)
- [GO-2025-3645 - Kubernetes did not effectively clear service account credentials in k8s.io/kubernetes](https://junglewise.ai/threats/cve-2019-11243-kubernetes-did-not-effectively-clear-service-account-credentials)