CVE-2026-42559

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.

CVSS v3 8.8 HIGH

8.8^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.8 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/modelcontextprotocol/rust-sdk/commit/8e22aa2de28df5a285eed87c11cd89bf15fa90d3
https://github.com/modelcontextprotocol/rust-sdk/issues/815
https://github.com/modelcontextprotocol/rust-sdk/issues/822
https://github.com/modelcontextprotocol/rust-sdk/pull/764
https://github.com/modelcontextprotocol/rust-sdk/security/advisories/GHSA-89vp-x53w-74fx

Configurations

No configuration.

History

26 Oct 2026, 14:10

Type	Values Removed	Values Added
Summary		(es) RMCP es un SDK oficial de Rust para el Protocolo de Contexto del Modelo. Antes de la versión 1.4.0, el transporte de servidor HTTP Streamable del crate rmcp (crates/rmcp/src/transport/streamable_http_server/) no validaba el encabezado Host entrante. Esto permitía que un sitio web público malicioso, a través de un ataque de DNS rebinding, enviara solicitudes autenticadas a un servidor MCP ejecutándose en la interfaz de loopback o de red privada de la víctima. Esta vulnerabilidad está corregida en la versión 1.4.0.

Information

Published : 2026-05-14 15:16

Updated : 2026-10-26 14:10

NVD link : CVE-2026-42559

Mitre link : CVE-2026-42559

CVE.ORG link : CVE-2026-42559

JSON object : View

Products Affected

No product.

CWE

CWE-346

Origin Validation Error

CWE-350

Reliance on Reverse DNS Resolution for a Security-Critical Action

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