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.
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.002 (12.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 13th percentile — 12.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Lfprojects Mcp Python Sdk
- Modelcontextprotocol Python-Sdk — versions < 1.28.1
Weakness classification (CWE)
References
- github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7q-gjh5-9… (Vendor Advisory)
- github.com/modelcontextprotocol/python-sdk/pull/2992 (Patch, Issue Tracking)
- github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2… (Patch)
- github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1 (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.