CVE-2026-33252

MEDIUM EPSS 7.5%
Published Mar 24, 20263mo ago · Modified Jun 17, 20262w ago
6.5 CVSS 3.1
Medium
Find Similar
Published Mar 24, 2026 3mo ago
Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score
6.5
Exploitability
2.8
Impact
3.6
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction Required
Scope Unchanged
Confidentiality None
Integrity High
Availability None

Threat Intelligence

EPSS Exploit Probability
7.5% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-352 Cross-Site Request Forgery (CSRF) Authentication

Affected Products 1

VendorProductVersionRange
lfprojectsmcp_go_sdk* <1.4.1

References 2

  • github.com https://github.com/modelcontextprotocol/go-sdk/commit/a433a831d6e5d5ac3b9e625a8095aa8eaa040dfc
    Patch
  • github.com https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-89xv-2j6f-qhc8
    PatchVendor Advisory

Remediation

  • github.com https://github.com/modelcontextprotocol/go-sdk/commit/a433a831d6e5d5ac3b9e625a8095aa8eaa040dfc
    Patch
  • github.com https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-89xv-2j6f-qhc8
    PatchVendor Advisory