Maciej-Kisiel

**Name of the Vulnerable Software and Affected Versions** Go MCP SDK versions prior to 1.4.0 **Description** The Go MCP SDK, utilizing Go's standard encoding/json, did not enable DNS rebinding protection by default for HTTP-based servers prior to version 1.4.0. When an HTTP-based MCP server was run on localhost without authentication using `StreamableHTTPHandler` or `SSEHandler`, a malicious website could exploit DNS rebinding to bypass same-origin policy restrictions and send requests to the local MCP server. This could allow an attacker to invoke tools or access resources exposed by the MCP server on behalf of the user. **Recommendations** Update to version 1.4.0 or later.