RMCP is an official Rust SDK for the Model Context Protocol. Prior to version 1.4.0, the rmcp crate's Streamable HTTP server transport (crates/rmcp/src/transport/streamable_http_server/) did not validate the incoming Host header. This allowed a malicious public website, via a DNS rebinding attack, to send authenticated requests to an MCP server running on the victim's loopback or private-network interface.
This vulnerability is fixed in 1.4.0.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
Required
User action required
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service
CVSS Vector v3.1
Weakness Type (CWE)
References 5
https://github.com/modelcontextprotocol/rust-sdk/commit/8e22aa2de28df5a285eed87…
security-advisories@github.com
https://github.com/modelcontextprotocol/rust-sdk/issues/815
security-advisories@github.com
https://github.com/modelcontextprotocol/rust-sdk/issues/822
security-advisories@github.com
https://github.com/modelcontextprotocol/rust-sdk/pull/764
security-advisories@github.com
https://github.com/modelcontextprotocol/rust-sdk/security/advisories/GHSA-89vp-…
security-advisories@github.com