CVE-2026-59950

MCP Python SDK: WebSocket server transport does not support Host/Origin validation

Published: Jul 15, 2026Updated: Jul 17, 2026 Sources: CVE List NVDCWE-346

8.1HIGH

Description

The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to 1.28.1, the deprecated mcp.server.websocket.websocket_server transport accepted WebSocket handshakes without applying Host or Origin header validation, leaving no SDK-level way to restrict which origins could connect to applications that exposed that transport. This issue is fixed in version 1.28.1.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:NPrivileges Required

None

UI:RUser Interaction

Required

Scope

S:UScope

Unchanged

Impact

C:HConfidentiality

High

I:HIntegrity

High

A:NAvailability

None

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Weaknesses

CWE-346 CWE-1385

Affected Products

lfprojects

oss-projectaka mlflow, valkey, model context protocol servers, mcp servers

mcp python sdkMixed

AI / ML / notebook-mlops

modelcontextprotocol

oss-projectaka model context protocol, mcp

python-sdkMixed

AI / ML / ai-agent-tooling

Exploitability

Official Patch Available

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References

https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266

github.com

https://github.com/modelcontextprotocol/python-sdk/pull/2992

github.com

https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1

github.com

and 1 more references View all →

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