universal-tool-calling-protocol python-utcp up to 1.1.1 HTTPS Endpoint register_manual server-side request forgery

Summaryinfo

A vulnerability was found in universal-tool-calling-protocol python-utcp up to 1.1.1. It has been classified as critical. This issue affects the function register_manual of the component HTTPS Endpoint. Performing a manipulation results in server-side request forgery. This vulnerability is known as CVE-2026-44661. Remote exploitation of the attack is possible. No exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as critical has been found in universal-tool-calling-protocol python-utcp up to 1.1.1. This affects the function register_manual of the component HTTPS Endpoint. The manipulation with an unknown input leads to a server-side request forgery vulnerability. CWE is classifying the issue as CWE-918. The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-44661 since 05/07/2026. The exploitability is told to be difficult. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available.

Upgrading to version 1.1.2 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-30479). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Programming Language Software

Vendor

• universal-tool-calling-protocol

Name

• python-utcp

Version

• 1.1.0
• 1.1.1

Website

• Product: https://github.com/universal-tool-calling-protocol/python-utcp/

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If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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