CVE-2026-45366: Universal-Tool-Calling-Protocol TypeScript-Utcp

Medium severity, CVSS 4.7. EPSS: 0.2% chance of exploitation in the next 30 days.

typescript-utcp is a typescript implementation of UTCP. Prior to 1.1.2, the @utcp/http package is vulnerable to a blind Server-Side Request Forgery (SSRF) caused by a trust-boundary inconsistency between manual discovery and tool invocation. registerManual() validates the discovery URL against an HTTPS / loopback allowlist, but callTool() reuses the resolved toolCallTemplate.url directly without revalidating, and the OpenApiConverter 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 converter then produces tools whose URL points at internal services on the agent host. This vulnerability is fixed in 1.1.2.

Affected products

• Universal-Tool-Calling-Protocol TypeScript-Utcp: before 1.1.2 (fixed in 1.1.2)

Published 2026-05-28. Last modified 2026-07-21.