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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
High
Difficult to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products
modelcontextprotocol:python-sdk
References 7
https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-w4f…
https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-w4fh-qvv9-3v23
https://github.com/modelcontextprotocol/python-sdk/pull/3447
https://github.com/modelcontextprotocol/python-sdk/pull/3447
https://github.com/modelcontextprotocol/python-sdk/pull/3451
https://github.com/modelcontextprotocol/python-sdk/pull/3451
https://github.com/modelcontextprotocol/python-sdk/commit/0c9136841ff092987a207…
https://github.com/modelcontextprotocol/python-sdk/commit/0c9136841ff092987a20700ff9c2c9789bda2f40
https://github.com/modelcontextprotocol/python-sdk/commit/8c2fa6eabacde869d7556…
https://github.com/modelcontextprotocol/python-sdk/commit/8c2fa6eabacde869d75568e33b9d466b58c2f512
https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.30.0
https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.30.0
https://github.com/modelcontextprotocol/python-sdk/releases/tag/v2.2.0
https://github.com/modelcontextprotocol/python-sdk/releases/tag/v2.2.0