CVE-2026-42559
High
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.
SeverityHigh
CVSS8.8
Exploit probability—
ProductDynoxide-rs
PublishedMay 14, 2026
First seenMay 14, 2026
Weakness typeCWE-346CWE-346CWE-350CWE-350
How to fix
Update
- dynoxide-rs0.9.13 or later
- dynoxide0.9.13 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| dynoxide-rscrates.io | 0.9.3 ≤ v < 0.9.13 | 0.9.13 |
| dynoxidenpm | 0.9.3 ≤ v < 0.9.13 | 0.9.13 |
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