CVE-2026-116684

Published: Oct 27, 2026Modified: Oct 28, 2026

6.8

Vector

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

Exploitability: 1.6 / Impact: 5.2

Source: security-advisories@github.com (Secondary)

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, server-side bearer authentication configured through AuthSettings with token_verifier accepts a valid token issued for another service when the authorization server serves multiple resources and the TokenVerifier does not independently validate the aud audience. This resource-confusion flaw lets a token holder authenticate to the wrong MCP server and exercise that token's resulting access. This issue is fixed in versions 1.30.0 and 2.2.0.

Related CWEs

Incorrect Authorization

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions.

References (7)

https://github.com/modelcontextprotocol/python-sdk/commit/0c9136841ff092987a20700ff9c2c9789bda2f40

Source: security-advisories@github.com

https://github.com/modelcontextprotocol/python-sdk/commit/8c2fa6eabacde869d75568e33b9d466b58c2f512

Source: security-advisories@github.com

https://github.com/modelcontextprotocol/python-sdk/pull/3447

Source: security-advisories@github.com

https://github.com/modelcontextprotocol/python-sdk/pull/3451

Source: security-advisories@github.com

https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.30.0

Source: security-advisories@github.com

https://github.com/modelcontextprotocol/python-sdk/releases/tag/v2.2.0

Source: security-advisories@github.com

https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-w4fh-qvv9-3v23

Source: security-advisories@github.com

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