utcp-http has an OAuth2 `tokenUrl` Trust Boundary Bypass in OpenAPI Conversion
### Summary
The `utcp-http` library (<= 1.1.3) unconditionally trusts the `tokenUrl` field embedded in remote OpenAPI security schemes. When a victim registers an attacker-controlled OpenAPI spec and invokes any generated OAuth2-protected tool, the library POSTs the victim's `client_id` and `client_secret` to the attacker-supplied token endpoint without any URL validation. The same `ensure_secure_url()` guard applied to discovery URLs and tool invocation URLs is absent for the OAuth2 token endpoint, creating a credential-exfiltration path.
### Details
`utcp-http` supports automatic tool generation from remote OpenAPI specifications. During
utcp-http SSRF: HTTP tool invocation follows redirects without re-validating the target
## Summary
`HttpCommunicationProtocol.call_tool` validates only the pre-redirect tool URL, then issues the request with redirects enabled and never re-checks where it lands. A tool whose endpoint is an attacker-controlled public URL can therefore `302`-redirect the UTCP client into an internal service including the cloud metadata endpoint and the response body is returned to the tool caller. This is a working SSRF + internal-data-exfiltration primitive.
This is the redirect invariant of the SSRF class fixed in GHSA-39j6-4867-gg4w; that fix added an invocation-time URL check but left the redirect hop unguarded. This vector bypasses the GHSA-
python-utcp: SSRF via attacker-controlled OpenAPI servers[0].url in HTTP communication protocol
python-utcp is the python implementation of UTCP. Prior to 1.1.3, 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, and the OpenAPI converter blindly trusts whatever servers[0].url an attacker-hosted spec declares. An attacker who hosts a malicious OpenAPI spec on a legitimate HTTPS endpoint can declare e.g. servers: [{ url: "http