High 7.6Published Jul 15, 2026

CVE-2026-59950MCP Python SDK: WebSocket server transport does not support Host/Origin validation

Updated under an hour ago (Oct 27, 2026, 9:00 AM ET)

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It affects modelcontextprotocol python-sdk and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for modelcontextprotocol python-sdk

Exploited in the last 30 days

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: 7.6 HIGH (v4.0, CNA)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
Weakness (CWE): CWE-346, CWE-1385
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Jul 17, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

modelcontextprotocol python-sdk modelcontextprotocol:python_sdk (from the name)	before 1.28.1	CNA record
lfprojects mcp_python_sdk lfprojects:mcp_python_sdk	before 1.28.1	NVD

References

References

https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7q-gjh5-988w	x-refsource-confirm, vendor-advisory
https://github.com/modelcontextprotocol/python-sdk/pull/2992	x-refsource-misc, issue-tracking, patch
https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266	x-refsource-misc, patch
https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1	x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.