GHSA-89xv-2j6f-qhc8

Source

https://github.com/advisories/GHSA-89xv-2j6f-qhc8

Import Source

https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-89xv-2j6f-qhc8/GHSA-89xv-2j6f-qhc8.json

JSON Data

https://api.osv.dev/v1/vulns/GHSA-89xv-2j6f-qhc8

Aliases

CVE-2026-33252

Published

2026-03-19T16:42:40Z

Modified

2026-03-19T16:49:39.411081Z

Severity

7.1 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L CVSS Calculator

Summary

Cross-Site Tool Execution for HTTP Servers without Authorizatrion in github.com/modelcontextprotocol/go-sdk

Details

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.

Impact:

A malicious website may have been able to send cross-site POST requests with Content-Type: text/plain, which due to CORS-safelisted properties would reach the MCP message handling without any CORS preflight barrier.

Fix:

The SDK was modified to perform Content-Type header validation for POST requests and introduced a configurable protection for verifying the origin of the request in commit a433a83. Users are advised to update to v1.4.1 to use this additional protection.

Note: v1.4.1 requires Go 1.25 or later.

Credits:

Thank you to Lê Minh Quân for reporting the issue.

Database specific

{
    "github_reviewed": true,
    "cwe_ids": [
        "CWE-352"
    ],
    "github_reviewed_at": "2026-03-19T16:42:40Z",
    "nvd_published_at": null,
    "severity": "HIGH"
}

References

Affected packages

Go / github.com/modelcontextprotocol/go-sdk

Package

Name: github.com/modelcontextprotocol/go-sdk; View open source insights on deps.dev
Purl: pkg:golang/github.com/modelcontextprotocol/go-sdk

Affected ranges

Type: SEMVER
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

1.4.1

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-89xv-2j6f-qhc8/GHSA-89xv-2j6f-qhc8.json"

last_known_affected_version_range

"<= 1.4.0"