CVE-2026-59950

EUVD-2026-44798
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
8.1 HIGH
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 13.65%
Affected Products (NVD)
VendorProductVersion
lfprojectsmcp_python_sdk
𝑥
< 1.28.1
𝑥
= Vulnerable software versions
Common Weakness Enumeration
References
https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266
https://github.com/modelcontextprotocol/python-sdk/pull/2992
https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1
https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7q-gjh5-988w