{"id":"CVE-2026-101058","title":"python-utcp (pip package utcp-http) before 1.1.12 does not verify whether tool URLs declared in a hand-written UTCP manual point at the agent's own loopback interface when that manual is discovered from a remote, non-loopback origin","summary":"python-utcp (pip package utcp-http) before 1.1.12 does not verify whether tool URLs declared in a hand-written UTCP manual point at the agent's own loopback interface when that manual is discovered from a remote, non-loopback origin. Bec…","severity":"medium","cvss":6.9,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N","cwe":["CWE-918"],"vendor":"universal-tool-calling-protocol","product":"python-utcp","affected":["python-utcp < 1.1.12"],"published":"2026-09-27","updated":"2026-09-27","sourceUpdated":"2026-09-27T18:16:31.973","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-101058","references":[{"url":"https://github.com/universal-tool-calling-protocol/python-utcp/security/advisories/GHSA-8vxx-v7r9-948g","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/python-utcp-before-1.1.12-ssrf-via-remote-http-manual","label":"disclosure@vulncheck.com"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-09-27T17:56:02.210Z","slug":"CVE-2026-101058","body":"## Overview\n\npython-utcp (pip package utcp-http) before 1.1.12 does not verify whether tool URLs declared in a hand-written UTCP manual point at the agent's own loopback interface when that manual is discovered from a remote, non-loopback origin. Because ensure_secure_url intentionally permits loopback HTTP for local development and native manuals bypassed the loopback check performed by the OpenAPI converter, an attacker who can serve a UTCP manual that a victim registers can cause the client to issue requests to services bound only to 127.0.0.1 on the victim host and have the response bodies returned to the caller (server-side request forgery). The http, sse and streamable_http protocols are all affected. Reach is limited to loopback, and exploitation further requires a loopback service that answers unauthenticated requests with useful data. Fixed in utcp-http 1.1.12, which rejects manuals fetched from a non-loopback origin that declare loopback tool URLs, keyed off the final post-redirect discovery URL.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":38,"depthScoreParts":{"impact":38,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}