Vulnerability-Lookup

CVE-2026-44661 (GCVE-0-2026-44661)

Vulnerability from cvelistv5 – Published: 2026-05-14 20:12 – Updated: 2026-05-15 11:25

Title

python-utcp: SSRF via attacker-controlled OpenAPI servers[0].url in HTTP communication protocol

Summary

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://127.0.0.1:9090" }] or servers: [{ url: "http://169.254.169.254" }]; the OpenAPI converter then produces tools whose URL points at internal services on the agent host. All three HTTP-class protocols (utcp_http.http, utcp_http.streamable_http, utcp_http.sse) shared the same gap. This vulnerability is fixed in 1.1.3.

Severity

4.7 (Medium)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

CWE

CWE-918 - Server-Side Request Forgery (SSRF)

Assigner

GitHub_M

References

1 reference

URL	Tags
https://github.com/universal-tool-calling-protoco…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version
universal-tool-calling-protocol	python-utcp	Affected: < 1.1.2

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-44661

Vulnerability from fkie_nvd - Published: 2026-05-14 21:16 - Updated: 2026-05-15 14:53

Severity

4.7 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/universal-tool-calling-protocol/python-utcp/security/advisories/GHSA-39j6-4867-gg4w

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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://127.0.0.1:9090\" }] or servers: [{ url: \"http://169.254.169.254\" }]; the OpenAPI converter then produces tools whose URL points at internal services on the agent host. All three HTTP-class protocols (utcp_http.http, utcp_http.streamable_http, utcp_http.sse) shared the same gap. This vulnerability is fixed in 1.1.3."
    }
  ],
  "id": "CVE-2026-44661",
  "lastModified": "2026-05-15T14:53:48.823",
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        "type": "Secondary"
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GHSA-39J6-4867-GG4W

Vulnerability from github – Published: 2026-05-07 22:32 – Updated: 2026-05-15 23:45

Summary

utcp-http vulnerable to SSRF via attacker-controlled OpenAPI servers[0].url in HTTP communication protocol

Details

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 in #83.

Severity

4.7 (Medium)


                  
                    CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

Show details on source website

JSON

To clipboard

{
  "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": "2026-05-14T21:16:47Z",
    "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": "2026-05-15T23:45:57Z",
  "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": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44661"
    },
    {
      "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"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-44661 (GCVE-0-2026-44661)

FKIE_CVE-2026-44661

GHSA-39J6-4867-GG4W

Summary

Impact

Affected versions

Patched versions

Patch

Workarounds

Credit

Tags

Sightings

Nomenclature