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CVE-2026-59950

CVE-2026-59950 · MCP Python SDK: WebSocket server transport does not support Host/Origin validation

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 7.6 · High · EPSS 0.2% · Fix available

Published
Updated

Stack: python

Affected products and versions

  • python-sdk

    Versions
    • < 1.28.1: Affected

    No fix published

  • mcp PyPI

    Versions
    • 0.9.1
    • 1.0.0
    • 1.1.0
    • 1.1.1
    • 1.1.2
    • 1.1.3
    • 1.10.0
    • 1.10.1
    • 1.11.0
    • 1.12.0
    • 1.12.1
    • 1.12.2
    • 1.12.3
    • 1.12.4
    • 1.13.0
    • 1.13.1
    • 1.14.0
    • 1.14.1
    • 1.15.0
    • 1.16.0
    • 1.17.0
    • 1.18.0
    • 1.19.0
    • 1.2.0
    • 1.2.0rc1
    • 1.2.1
    • 1.20.0
    • 1.21.0
    • 1.21.1
    • 1.21.2
    • 1.22.0
    • 1.23.0
    • 1.23.1
    • 1.23.2
    • 1.23.3
    • 1.24.0
    • 1.25.0
    • 1.26.0
    • 1.27.0
    • 1.27.1
    • 1.27.2
    • 1.28.0
    • 1.3.0
    • 1.3.0rc1
    • 1.4.0
    • 1.4.1
    • 1.5.0
    • 1.6.0
    • 1.7.0
    • 1.7.1
    • 1.8.0
    • 1.8.1
    • 1.9.0
    • 1.9.1
    • 1.9.2
    • 1.9.3
    • 1.9.4
    Affected ranges
    • ECOSYSTEM: < 1.28.1

    Update to 1.28.1

Original sources

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