CVE-2026-46519: MCP Server Kubernetes: Tool Access Control Bypass via Presentation-Layer Filtering Without Execution-Layer Enforcement

May 21, 2026 (updated June 12, 2026)

mcp-server-kubernetes exposes three environment variables (ALLOW_ONLY_READONLY_TOOLS, ALLOW_ONLY_NON_DESTRUCTIVE_TOOLS, ALLOWED_TOOLS) documented as access controls for restricting which Kubernetes operations are available. These controls are enforced at the tool discovery layer (tools/list) but not at the execution layer (tools/call). Any client that knows a tool name can invoke it directly regardless of the configured restriction mode. The access control was effectively cosmetic.

Fixed in v3.6.0.

References

github.com/Flux159/mcp-server-kubernetes/releases/tag/v3.6.0
github.com/Flux159/mcp-server-kubernetes/security/advisories/GHSA-cr22-wjx7-2w6m
github.com/advisories/GHSA-cr22-wjx7-2w6m
nvd.nist.gov/vuln/detail/CVE-2026-46519

Code Behaviors & Features

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