Vulnerability in Lfprojects Mcp Python Sdk
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.
EPSS: 0.002 (13.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N.
Affected products
- Lfprojects Mcp_python_sdk
- Modelcontextprotocol Python-sdk — versions < 1.28.1
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC, Issue Tracking)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC, Release Notes)
Frequently asked questions
- What is CVE-2026-59950?
- CVE-2026-59950 is a high-severity vulnerability in Lfprojects Mcp Python Sdk, classified under Origin Validation Error. CVSS score: 8.1/10. Published 2026-07-15.
- How severe is CVE-2026-59950?
- High severity. CVSS v3 base score is 8.1 out of 10.