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CVE-2026-42559

RMCP: DNS rebinding vulnerability in rmcp Streamable HTTP server transport PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
modelcontextprotocol / rust-sdkaffected < 1.4.0

CWE

CWE-346, CWE-350

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.