Server-Side Request Forgery in Python-UTCP by Universal Tool Calling Protocol

CVE-2026-101058

What is CVE-2026-101058?

The python-utcp package, specifically versions prior to 1.1.12, contains a vulnerability that allows an attacker to exploit server-side request forgery (SSRF). This occurs when tool URLs in a UTCP manual, written by hand, are not properly validated to ensure they only point to the local loopback interface. If a malicious actor serves a UTCP manual and convinces a victim to register it, the victim's client may unwittingly send requests to services bound exclusively to the localhost (127.0.0.1). Consequently, this could result in sensitive information being exposed, as the attacker can retrieve the responses from those services. The vulnerability primarily affects the HTTP, SSE, and streamable HTTP protocols. It can be mitigated by upgrading to version 1.1.12, which implements checks to reject non-loopback manuals declaring loopback URLs.

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