@cardano402/mcp-server missing spending limits, LAN-exposed HTTP transport, and SSRF via catalog.server.url

Summary

## Summary `@cardano402/mcp-server` versions `<= 0.1.1` ship three security gaps that can lead to unauthorized fund movement when the package is used as designed (an MCP server exposing Cardano payment tools to an

## Impact ### 1. No spending limits on signed payments An LLM (or prompt-injected LLM) calling tools registered by the MCP server can invoke them in a loop. Each call signs a real Cardano transaction for the catalog-advertised amount. There is no per-call cap, daily ceiling, MCP elicitation/confirmation step, or recipient allowlist. The `MAINNET=true` env-var guardrail can be bypassed by any LLM with shell-tool access. Worst case: full wallet drain.

### 2. HTTP transport binds 0.0.0.0 without authentication `cardano402-mcp --transport http` listens on all interfaces with no `Origin` allowlist, no bearer-token requirement, and no CORS check. Anyone on the same LAN can POST MCP `tools/call` and trigger signed payments from the operator's wallet.

### 3. SSRF via `catalog.server.url` A malicious catalog can declare a `server.url` pointing at internal infrastructure (e.g. `http://169.254.169.254/latest/meta-data`). The `allowInsecure` guard in 0.1.1 only checks the catalog URL itself, not the `server.url` it returns. `endpoint.path` is also not normalized, so `..` traversal or absolute URLs work.

## Patches Fixed in `@cardano402/mcp-server@0.1.2`: - Per-call and per-day spending limits (default 5 ADA / 50 ADA) + optional recipient allowlist + MCP `elicitation/create` confirmation hook. - HTTP transport defaults to `127.0.0.1`; non-loopback requires `--http-bearer-token`; per-request `Origin` allowlist + bearer check. - `catalog.server.url` validated against private-CIDR rules (RFC1918, RFC4193, link-local, CGNAT, multicast, IPv4-mapped IPv6, loopback) unless `CARDANO402_ALLOW_INSECURE=true`. - `endpoint.path` rejected if it contains `..`, NUL, whitespace/CRLF, an absolute URL, or `//host/...`. - Per-tool mainnet opt-in via `--mainnet-confirmed-tools`.

## Workarounds for 0.1.1 users - Do not run with `--transport http` on an untrusted network; use `--transport stdio` (default). - Only point the server at catalogs you control or have audited. - Use a low-balance hot wallet, never your main wallet. - Avoid `MAINNET=true` until upgraded to 0.1.2.