CVE-2026-44661 MEDIUM

CVE-2026-44661: python-utcp: SSRF via attacker-controlled OpenAPI servers[0].url in HTTP communication protocol

Vendor Universal-Tool-Calling-Protocol
Product python-utcp
Weakness CWE-918 · SSRF
Published May 14, 2026
Last update May 15, 2026

CVSS base score

4.7/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction Required
Confidentiality Low
Integrity Low

CVSS vector

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

What the vulnerability does

Description

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.

Key dates

Disclosure timeline

May 14, 2026 CVE published
May 15, 2026 Record updated