Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Lfprojects | Mcp Python Sdk | < 1.28.1 |
Related Weaknesses (CWE)
References
- https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0Patch
- https://github.com/modelcontextprotocol/python-sdk/pull/2992Issue TrackingPatch
- https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1Release Notes
- https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7qVendor Advisory
FAQ
What is CVE-2026-59950?
CVE-2026-59950 is a vulnerability with a CVSS score of 8.1 (HIGH). 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 WebSock...
How severe is CVE-2026-59950?
CVE-2026-59950 has been rated HIGH with a CVSS base score of 8.1/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-59950?
Check the references section above for vendor advisories and patch information. Affected products include: Lfprojects Mcp Python Sdk.