CVE-2026-33252
The Go MCP SDK used Go's standard encoding/json.
Published Mar 24, 2026 · updated Jun 17, 2026 · lfprojects mcp go sdk
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 requests without validating the header and without requiring . 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.
Code
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Timeline
Detection, updates, and resolution for this record.
Mar 24, 2026 · NIST NVD
Detected
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 requests without validating the header and without requiring . 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 t
Jun 17, 2026 · NIST NVD
Updated
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 requests without validating the header and without requiring . 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 t
Affected
- cpe lfprojects/mcp go sdkversion unspecified
Sources
- CVE.orgVulnerability recordCVE-2026-33252
Official CVE identifier
cve.org - NIST NVDVulnerability recordCVE-2026-33252
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 requests without validating the header and without requiring . In deployments with
nvd.nist.gov