VULNERABILITY INTELLIGENCE

CVE-2026-33252

CVSS score7.1 HIGH
EPSS probability0.18%
CISA KEVNot currently listed
Published2026-03-24
Last modified2026-06-17
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L

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.

Weakness classification

  • CWE-352: Cross-Site Request Forgery (CSRF)

Primary references