# CVE-2026-59950

## Summary

- **CVE ID:** CVE-2026-59950
- **Severity:** HIGH
- **CVSS Score:** 7.6 (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)
- **CWE:** CWE-346, CWE-1385
- **Published:** Jul 15, 2026
- **Last Modified:** Jul 17, 2026

## 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.

## Affected Products

- modelcontextprotocol — python-sdk (< 1.28.1)

## References

- [CNA](https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7q-gjh5-988w)
- [CNA](https://github.com/modelcontextprotocol/python-sdk/pull/2992)
- [CNA](https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266)
- [CNA](https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.23%
- **EPSS Percentile:** 13.9

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._