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CVE-2026-59950

MCP Python SDK: WebSocket server transport does not support Host/Origin validation

Published: Jul 15, 2026Updated: Jul 17, 2026 Sources: CVE List NVDCWE-346
8.1HIGH
NVD MITRE
EPSS Score
0.1%
Top 95.4%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
Not available

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:RS:UC:HI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:NAvailability
None
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Weaknesses

CWE-346CWE-1385

Affected Products

lfprojects
oss-projectaka model context protocol servers, valkey, mcp servers, mlflow
mcp python sdkMixed
AI / ML / notebook-mlops
modelcontextprotocol
oss-projectaka model context protocol, mcp
python-sdkMixed
AI / ML / ai-agent-tooling

Exploitability

Official Patch Available
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References

https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266
github.com
https://github.com/modelcontextprotocol/python-sdk/pull/2992
github.com
https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1
github.com
and 1 more references View all →

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