CVE-2026-116684
Published:October 27, 2026
Updated:October 28, 2026
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.
Affected Packages
mcp (CONDA):
Affected version(s) >=1.10.0 <1.30.0Fix Suggestion:
Update to version 1.30.0mcp (CONDA):
Affected version(s) >=2.0.0 <2.2.0Fix Suggestion:
Update to version 2.2.0https://github.com/modelcontextprotocol/python-sdk.git (GITHUB):
Affected version(s) >=v2.0.0 <v2.2.0Fix Suggestion:
Update to version v2.2.0https://github.com/modelcontextprotocol/python-sdk.git (GITHUB):
Affected version(s) >=v1.10.0 <v1.30.0Fix Suggestion:
Update to version v1.30.0mcp (PYTHON):
Affected version(s) >=1.10.0 <1.30.0Fix Suggestion:
Update to version 1.30.0mcp (PYTHON):
Affected version(s) >=2.0.0 <2.2.0Fix Suggestion:
Update to version 2.2.0Related Resources (8)
Do you need more information?
Contact UsCVSS v4
Base Score:
7.6
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
NONE
Vulnerable System Confidentiality
HIGH
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
6.8
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Incorrect Authorization