A flaw in python-utcp (pip package utcp-http) before version 1.1.12 allows a remote attacker to cause a client to request services bound to the victim’s loopback interface. The client processes a UTCP manual that the attacker supplies from a remote source and accepts loopback URLs because the manual bypasses the normal loopback check. This is a classic SSRF (CWE-918) that can return the response body of any locally accessible service that does not require authentication. The impact is disclosure of internal data and potentially further compromise of the local host.

The vulnerability affects the universal-tool-calling-protocol python-utcp package (pip package utcp-http). All releases earlier than 1.1.12 are susceptible; version 1.1.12 and later include a fix that rejects manuals fetched from non-loopback origins that contain loopback URLs.

The CVSS score of 7.1 indicates a high potential for damage. EPSS is not available, so an estimated exploitation probability cannot be determined from the data. The vulnerability is not listed in the CISA KEV catalog. Exploitation requires an attacker who can serve a UTCP manual and a victim that registers it; the victim’s client will then contact services bound only to 127.0.0.1 and return their responses to the attacker. The attack vector is primarily server-side request forgery through a manual file sent from a remote origin.