CVE-2026-42559
Deferred Deferred - Pending Action
BaseFortify

Publication date: 2026-05-14

Last updated on: 2026-05-14

Assigner: GitHub, Inc.

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.
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Meta Information
Published
2026-05-14
Last Modified
2026-05-14
Generated
2026-06-10
EPSS Evaluated
2026-06-08
NVD
CVE-2026-42559
Affected Vendors & Products
Currently, no data is known.
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-346 The product does not properly verify that the source of data or communication is valid.
CWE-350 The product performs reverse DNS resolution on an IP address to obtain the hostname and make a security decision, but it does not properly ensure that the IP address is truly associated with the hostname.
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