CVE-2026-33252

Published Mar 24, 2026

Last updated 8 days ago

Overview

Description
The Go MCP SDK used Go's standard encoding/json. Prior to version 1.4.1, the Go SDK's Streamable HTTP transport accepted browser-generated cross-site `POST` requests without validating the `Origin` header and without requiring `Content-Type: application/json`. In deployments without Authorization, especially stateless or sessionless configurations, this allows an arbitrary website to send MCP requests to a local server and potentially trigger tool execution. Version 1.4.1 contains a patch for the issue.
Source
security-advisories@github.com
NVD status
Analyzed
Products
mcp_go_sdk

Risk scores

CVSS 3.1

Type
Primary
Base score
6.5
Impact score
3.6
Exploitability score
2.8
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Severity
MEDIUM

Weaknesses

security-advisories@github.com
CWE-352

Social media

Hype score
Not currently trending

Configurations