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.
Published: 2026-05-14
Score: 8.8 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-89vp-x53w-74fx rmcp Streamable HTTP server transport has a DNS rebinding vulnerability
History

Thu, 14 May 2026 16:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Thu, 14 May 2026 15:15:00 +0000

Type Values Removed Values Added
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.
Title RMCP: DNS rebinding vulnerability in rmcp Streamable HTTP server transport
Weaknesses CWE-346
CWE-350
References
Metrics cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'}


Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-14T16:00:33.149Z

Reserved: 2026-04-28T16:56:50.192Z

Link: CVE-2026-42559

cve-icon Vulnrichment

Updated: 2026-05-14T16:00:29.092Z

cve-icon NVD

Status : Deferred

Published: 2026-05-14T15:16:46.750

Modified: 2026-05-14T17:19:49.973

Link: CVE-2026-42559

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-14T16:30:24Z

Weaknesses