CVE-2026-71208: KubeSphere - SSRF via Unvalidated Cluster CRD Connection Endpoint in Cluster Reconciliation

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-05 · updated 2026-08-26
Weakness: CWE-918

Description

KubeSphere's cluster-controller reconciliation (pkg/utils/clusterclient/clusterclient.go, addCluster) processes every Cluster custom resource's connection configuration and immediately calls Discovery.ServerVersion against the CRD-specified Kubernetes API endpoint, which is parsed only for URL syntax (url.Parse) with no allow/deny-list for loopback, RFC1918 private ranges, link-local, or cloud-metadata addresses (e.g. 169.254.169.254).

Affected products

KubeSphere: from 4.0.0 through 4.1.3-rc.0

References

https://github.com/ashikmd7/kubeSphere/blob/main/SSRF%20via%20Cluster%20CRD%20KubeConfig/README.md
https://github.com/kubesphere/kubesphere

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