Vulnerabilities CVE-2026-59950

CVE-2026-59950

High

Open

TLP:CLEAR

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

NVD CVE.org

Critical Infrastructure Supply Chain Attack

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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.

Details

CVSS Score: 7.6
EPSS Score ⓘ: 0.15%

4.6th percentile
CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Confidence: 90%
Published: Jul 15, 2026
Last Modified: Jul 17, 2026

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