The Go MCP SDK used Go's standard encoding/json. Prior to version 1.4.0, the Model Context Protocol (MCP) Go SDK does not enable DNS rebinding protection by default for HTTP-based servers. When an HTTP-based MCP server is run on localhost without authentication with 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 in those limited circumstances. This issue has been patched in version 1.4.0.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
None
No privileges needed
User Interaction
Passive
Minimal interaction
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v4.0
Weakness Type (CWE)
Vulnerable Products 1
| Configuration | From (including) | Up to (excluding) |
|---|---|---|
|
Lfprojects Mcp_Go_Sdk
cpe:2.3:a:lfprojects:mcp_go_sdk:*:*:*:*:*:*:*:*
|
— |
1.4.0
|
References 4
https://github.com/modelcontextprotocol/go-sdk/commit/67bd3f2e2b53ce11a16db8d97…
security-advisories@github.com
https://github.com/modelcontextprotocol/go-sdk/pull/760
security-advisories@github.com
https://github.com/modelcontextprotocol/go-sdk/releases/tag/v1.4.0
security-advisories@github.com
https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-xw59-hv…
security-advisories@github.com