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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2026-42559 Detail

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.


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://github.com/modelcontextprotocol/rust-sdk/commit/8e22aa2de28df5a285eed87c11cd89bf15fa90d3 GitHub, Inc.
https://github.com/modelcontextprotocol/rust-sdk/issues/815 GitHub, Inc.
https://github.com/modelcontextprotocol/rust-sdk/issues/822 GitHub, Inc.
https://github.com/modelcontextprotocol/rust-sdk/pull/764 GitHub, Inc.
https://github.com/modelcontextprotocol/rust-sdk/security/advisories/GHSA-89vp-x53w-74fx GitHub, Inc.

Weakness Enumeration

CWE-ID CWE Name Source
CWE-346 Origin Validation Error GitHub, Inc.  
CWE-350 Reliance on Reverse DNS Resolution for a Security-Critical Action GitHub, Inc.  

Change History

1 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-42559
NVD Published Date:
05/14/2026
NVD Last Modified:
05/14/2026
Source:
GitHub, Inc.