CVE-2026-59950
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.
Scoring
- Severity
- HIGH
- CVSS base score
- 7.6
- CVSS 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
- EPSS probability
- 0.23%
- CWE
- CWE-346, CWE-1385
- Published
- 2026-07-15
- Last modified
- 2026-07-17
Affected products
- modelcontextprotocol python-sdk
Weakness type
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