Description


The Model Context Protocol Python SDK is the official Python SDK for Model Context Protocol servers and clients. From 1.10.0 until 1.30.0 and 2.2.0, ClientSession, ClientSessionGroup, and Client tool calls validate server-declared outputSchema documents with jsonschema's default resolver, causing an unresolved $ref value to fetch an HTTP, HTTPS, or file URL from the client's network and filesystem context. A server can trigger blind requests or local-file reads and can stall every session in the process because resolution runs synchronously on the event loop without a timeout. This issue is fixed in versions 1.30.0 and 2.2.0.

Related CPE's


Could not find any relations

Weaknesses



CWE-918

CVSS impact metrics


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

6.5 · Medium

Information


Source identifier

[email protected]

Vulnerability status

Deferred

Published

2026-10-27T20:17:13.740Z

20 hours ago

Last modified

2026-10-28T15:24:56.033Z

56 minutes ago