cvedb.io
CVE-2026-42559
HIGH · CVSS 8.8
EPSS exploitation probability: 0%
Published 2026-05-14T15:16:46.750 · Last modified 2026-06-17T10:48:02.220

Summary

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.

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References

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