CVE-2026-44661

Description

## Summary The `utcp-http` plugin is vulnerable to a blind Server-Side Request Forgery (SSRF) caused by a trust-boundary inconsistency between manual discovery and tool invocation. `register_manual()` validates the discovery URL against an HTTPS / loopback allowlist, but `call_tool()` and `call_tool_streaming()` reuse the resolved `tool_call_template.url` directly without revalidating. An attacker who hosts a malicious OpenAPI spec on a legitimate HTTPS endpoint can declare `servers: [{ url: "http://169.254.169.254" }]` (or any internal address) in the spec; the OpenAPI converter blindly trusts that value and the tool becomes a blind SSRF primitive that exposes cloud metadata, internal services, and other firewalled-only endpoints to the LLM caller. All three HTTP-class protocols (`utcp_http.http`, `utcp_http.streamable_http`, `utcp_http.sse`) shared the same gap, plus a separate prefix-bypass: the previous `startswith("http://localhost")` check let URLs like `http://localhost.evil.com` through. ## Impact A remote attacker who can convince the agent (via the LLM context, prompt injection, or a tool-discovery surface) to register their HTTPS OpenAPI URL can: - Map internal networks behind the agent. - Read AWS/GCP IAM credentials from cloud metadata endpoints (`http://169.254.169.254`, `http://metadata.google.internal`). - Reach unauthenticated internal services (Elasticsearch, Redis HTTP, internal admin panels). - Have responses returned to the LLM, which combined with prompt injection enables exfiltration back to the attacker. ## Affected versions `utcp-http <= 1.1.1`. ## Patched versions `utcp-http 1.1.2`. ## Patch Commit: 5b16e43 on `dev`. - New `utcp_http._security` helper: `ensure_secure_url(url, context=...)` parses the URL with `urllib.parse.urlparse` and validates the hostname (not a string prefix) against the loopback set, closing the `localhost.evil.com` bypass. - All three protocols call `ensure_secure_url(url, context="manual discovery")` in `register_manual` (replacing the duplicated prefix check) and `ensure_secure_url(url, context="tool invocation")` immediately before each aiohttp request in `call_tool` / `call_tool_streaming`. The runtime check is the actual SSRF fix. - New regression tests in `test_security.py` pin the accept/reject decisions and explicitly cover the historical bypass cases. ## Workarounds For users who cannot upgrade immediately: - Refuse to call `register_manual` with any URL controlled by an untrusted party, even over HTTPS. - Restrict outbound network access from the host running the agent so internal addresses (RFC1918, 169.254.0.0/16, loopback for cloud metadata) are unreachable. ## Credit Discovered and reported by [@YLChen-007](https://github.com/YLChen-007) in #83.