Description
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.
References (5)
Core 5
Core References
X_Refsource_Confirm x_refsource_confirm
https://github.com/modelcontextprotocol/rust-sdk/security/advisories/GHSA-89vp-x53w-74fx
X_Refsource_Misc x_refsource_misc
https://github.com/modelcontextprotocol/rust-sdk/issues/815
X_Refsource_Misc x_refsource_misc
https://github.com/modelcontextprotocol/rust-sdk/issues/822
X_Refsource_Misc x_refsource_misc
https://github.com/modelcontextprotocol/rust-sdk/pull/764
X_Refsource_Misc x_refsource_misc
https://github.com/modelcontextprotocol/rust-sdk/commit/8e22aa2de28df5a285eed87c11cd89bf15fa90d3
Scores
CVSS v3
8.8
EPSS
0.0021
EPSS Percentile
11.5%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
no
Technical Impact
total
Details
CWE
CWE-346
CWE-350
Status
published
Products (2)
crates.io/rmcp
0 - 1.4.0crates.io
modelcontextprotocol/rust-sdk
< 1.4.0
Published
May 14, 2026
Tracked Since
May 14, 2026