CVE-2026-33252
MCP Go SDK Allows Cross-Site Tool Execution for HTTP Servers without Authorizatrion
- State
- Published
- Severity
- 7.1 High
- Published
- Mar 23, 2026
- Updated
- Mar 24, 2026
- Reserved
- Mar 18, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 7.1 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L | GitHub_M |
Weaknesses
- CWE-352 Cross-Site Request Forgery (CSRF)
Affected Products
| Product | Versions |
|---|---|
go-sdkmodelcontextprotocol |
|
References
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