CVE-2026-33252 HIGH

CVE-2026-33252: MCP Go SDK Allows Cross-Site Tool Execution for HTTP Servers without Authorizatrion

Vendor Modelcontextprotocol

Product go-sdk

Weakness CWE-352 · CSRF

Published March 23, 2026

Last update March 24, 2026

View on NVD All CVEs

CVSS base score

7.1/10

Attack vector Network

Attack complexity Low

Privileges required None

User interaction Required

Confidentiality None

Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

March 23, 2026 CVE published

March 24, 2026 Record updated

External resources

03References

NVD — National Vulnerability Database https://nvd.nist.gov/vuln/detail/CVE-2026-33252 CWE — Common Weakness Enumeration https://cwe.mitre.org/data/definitions/352.html

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04Related CVE

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