CVE-2026-116686
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 an
CVSS
6.5
Medium
EPSS
0.3%
p27
KEV
—
Exploit Today
8
0-100
Published: Oct 27, 2026 · Last modified: Oct 28, 2026 · CWE-918
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.
- github.comhttps://github.com/modelcontextprotocol/python-sdk/commit/5ebdfed4060d8e5b11b8e2348f86bad4d1fb8836
- github.comhttps://github.com/modelcontextprotocol/python-sdk/commit/6705402e246dc4eb1fcdf4d9902b78d3c9c36e1b
- github.comhttps://github.com/modelcontextprotocol/python-sdk/pull/3394
- github.comhttps://github.com/modelcontextprotocol/python-sdk/pull/3396
- github.comhttps://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.30.0
- github.comhttps://github.com/modelcontextprotocol/python-sdk/releases/tag/v2.2.0
- github.comhttps://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-rwrf-2pqf-9j8j