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CVE-2026-59950

35
FAUCET Score

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.

First published: Jul 15, 2026Last modified: Jul 15, 2026

Impacted Technologies

VendorProductVersion(s)CPE
< 1.28.1CPE matchmatch criteria
cpe:2.3:a:lfprojects:mcp_python_sdk:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

7.6HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
PASSIVE
VS Confidentiality
HIGH
VS Integrity
HIGH
VS Availability
NONE
SS Confidentiality
NONE
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.15%
Probability of exploitation in next 30 days
EPSS Percentile
4.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0015 is in the 3rd percentile among its peer group of 14,855 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.1 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
pippatch availablevia ghsa
Product: mcpFixed in: 1.28.1

Vendor Advisories (1)

pipGHSA-vj7q-gjh5-988whigh

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

Jul 16, 2026

References

github.com / modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266
Patch
github.com / modelcontextprotocol/python-sdk/pull/2992
Issue TrackingPatch
github.com / modelcontextprotocol/python-sdk/releases/tag/v1.28.1
Release Notes
github.com / modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7q-gjh5-988w
Vendor Advisory