CVE-2026-59950

HIGH
MEDIUM Priority: 0.02 BB Relevance: 65/100
Published: 2026-07-15 Modified: 2026-10-24 First seen: 2026-10-29 Status: active

Attack Surface

Network Low Complexity No Auth Conf. Impact Integ. Impact

CVSS Vector Breakdown

AV: Network
AC: Low
PR: None
UI: Passive
S: X
AT: Present
VC: High
VI: High
VA: None

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.

Weakness Classification (2)

Affected Software (1)

VendorProductVersion
lfprojects mcp_python_sdk < 1.28.1

Bug Bounty Relevance

65 / 100
✓ Network accessible
✓ No authentication
✓ Low complexity

CVSS Score

7.6 / 10.0 v4.0
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS — Exploitation Probability

0.23%
Raw Score 0.002310
Percentile 13.9%
Date 2026-10-29

EPSS Trend

2026-10-29
0.00231
2026-10-28
0.00231

Intelligence Sources

nvd ref →