CVE-2026-33252
MCP Go SDK Allows Cross-Site Tool Execution for HTTP Servers without Authorizatrion
CVSS Score
7.1
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-352 |
| Vendor | modelcontextprotocol |
| Product | go-sdk |
| Published | Mar 23, 2026 |
| Last Updated | Mar 24, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
Low
Affected Versions
modelcontextprotocol / go-sdk
< 1.4.1