{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.1.1"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "utcp-http"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.1.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44661"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-07T22:32:54Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nThe `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.\n\nAll 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.\n\n## Impact\n\nA 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:\n- Map internal networks behind the agent.\n- Read AWS/GCP IAM credentials from cloud metadata endpoints (`http://169.254.169.254`, `http://metadata.google.internal`).\n- Reach unauthenticated internal services (Elasticsearch, Redis HTTP, internal admin panels).\n- Have responses returned to the LLM, which combined with prompt injection enables exfiltration back to the attacker.\n\n## Affected versions\n\n`utcp-http \u003c= 1.1.1`.\n\n## Patched versions\n\n`utcp-http 1.1.2`.\n\n## Patch\n\nCommit: 5b16e43 on `dev`.\n\n- 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.\n- 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.\n- New regression tests in `test_security.py` pin the accept/reject decisions and explicitly cover the historical bypass cases.\n\n## Workarounds\n\nFor users who cannot upgrade immediately:\n- Refuse to call `register_manual` with any URL controlled by an untrusted party, even over HTTPS.\n- 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.\n\n## Credit\n\nDiscovered and reported by [@YLChen-007](https://github.com/YLChen-007) in #83.",
  "id": "GHSA-39j6-4867-gg4w",
  "modified": "2026-05-07T22:32:54Z",
  "published": "2026-05-07T22:32:54Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/universal-tool-calling-protocol/python-utcp/security/advisories/GHSA-39j6-4867-gg4w"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/universal-tool-calling-protocol/python-utcp"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "utcp-http vulnerable to SSRF via attacker-controlled OpenAPI servers[0].url in HTTP communication protocol"
}