CVE-2026-33252

Severity CVSS v4.0:

Pending analysis

Type:

CWE-352 Cross-Site Request Forgery (CSRF)

Publication date:

24/03/2026

Last modified:

24/03/2026

Description

The Go MCP SDK used Go&#39;s standard encoding/json. Prior to version 1.4.1, the Go SDK&#39;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.

Impact

Vector 3.x

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L CVSS v3.1 Severity and Metrics:

Base Score: 7.10 HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): Required
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): High
Availability (A): Low

Base Score 3.x

7.10

Severity 3.x

HIGH

CVE-2026-33252

Description

Impact

References to Advisories, Solutions, and Tools