CVE-2026-59950
MCP Python SDK: WebSocket server transport does not support Host/Origin validation
- State
- Published
- Severity
- 7.6 High
- Published
- Jul 15, 2026
- Updated
- Jul 17, 2026
- Reserved
- Jul 7, 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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 7.6 High | 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 | GitHub_M |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
python-sdkmodelcontextprotocol |
|
References
- https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7q-gjh5-988w
- https://github.com/modelcontextprotocol/python-sdk/pull/2992
- https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266
- https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1
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