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.
Published: 2026-07-15
Score: 7.6 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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History

Wed, 15 Jul 2026 20:45:00 +0000

Type Values Removed Values Added
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.
Title MCP Python SDK: WebSocket server transport does not support Host/Origin validation
Weaknesses CWE-1385
CWE-346
References
Metrics cvssV4_0

{'score': 7.6, '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'}

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-07-15T20:08:54.095Z

Reserved: 2026-07-07T18:49:15.607Z

Link: CVE-2026-59950

cve-icon Vulnrichment

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cve-icon NVD

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cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses
  • CWE-1385

    Missing Origin Validation in WebSockets

  • CWE-346

    Origin Validation Error