python-utcp before 1.1.12 SSRF via Remote HTTP Manual

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. 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.

Source published

27 Sep 2026 17:02:39 UTC

Source modified

30 Sep 2026 22:06:29 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 4.0 · 7.1 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N

CVSS 3.1 · 6.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N