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CVE-2026-59950

HIGH
7.6
CVSS 4.0
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.

Metadata

CVE ID
CVE-2026-59950
State
PUBLISHED
Assigner
GitHub_M
Reserved
2026-07-07 18:49 UTC
Published
2026-07-15 20:08 UTC
Last updated
2026-07-15 20:08 UTC
Primary CWE
CWE-346
CWE-346: Origin Validation Error
Vendor / Product
modelcontextprotocol / python-sdk
Sources
cve.org  ·  NVD

Severity & Metrics

7.6 HIGH CVSS 4.0
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
Affected products (1)
VendorProductPlatformVersions
modelcontextprotocol python-sdk — < 1.28.1
Weakness (CWE)
CWESourceDescription
CWE-1385 cna CWE-1385: Missing Origin Validation in WebSockets
CWE-346 cna CWE-346: Origin Validation Error
CVSS scores (1)
ScoreSeverityVersionSourceVector
7.6 HIGH 4.0 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
References (4)
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