Vulnerability · Published May 14, 2026 · Assigned by GitHub_M
CVE-2026-44661python-utcp: SSRF via attacker-controlled OpenAPI servers[0].url in HTTP communication protocol
Medium 4.7
In plain English
A medium-severity server-side request forgery in python-utcp from universal-tool-calling-protocol. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | utcp-http | 1.1.2 | GHSA-39j6-4867-gg4w |
| PyPI | utcp-http | 1.1.2 | PYSEC-2026-3396 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| universal-tool-calling-protocol | python-utcp | < 1.1.2 |
Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N