Skip to content
OpenAdvisories
Medium · 4.7 CVE-2026-44661 EUVD-2026-30479GHSA-39j6-4867-gg4wPYSEC-2026-3396

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

Published May 14, 2026 · Updated May 15, 2026 · Assigned by GitHub_M

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.

Affected products

VendorProductAffectedFixed
universal-tool-calling-protocol python-utcp < 1.1.2 —

Affected packages

EcosystemPackageAffectedFixedRecord
PyPI utcp-http < 1.1.2 1.1.2 GHSA-39j6-4867-gg4w

References