CVE-2026-42559

HIGH EPSS 11.6%
Published May 14, 20261mo ago · Modified Jun 17, 20261w ago
8.8 CVSS 3.1
High
Find Similar
Published May 14, 2026 1mo ago
Last Modified Jun 17, 2026 1w ago

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.

CVSS Details

Base Score
8.8
Exploitability
2.8
Impact
5.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction Required
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
11.6% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 2

CWE-346
CWE-350

References 5

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

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.