RMCP: DNS rebinding vulnerability in rmcp Streamable HTTP server transport_CVE-2026-42559

{
    "lastseen": "",
    "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.",
    "published": "2026-05-14T14:24:56.090Z",
    "modified": "2026-05-14T16:00:33.149Z",
    "type": "cve",
    "title": "RMCP: DNS rebinding vulnerability in rmcp Streamable HTTP server transport",
    "source": "GitHub_M",
    "references": "https://github.com/modelcontextprotocol/rust-sdk/security/advisories/GHSA-89vp-x53w-74fx\nhttps://github.com/modelcontextprotocol/rust-sdk/issues/815\nhttps://github.com/modelcontextprotocol/rust-sdk/issues/822\nhttps://github.com/modelcontextprotocol/rust-sdk/pull/764\nhttps://github.com/modelcontextprotocol/rust-sdk/commit/8e22aa2de28df5a285eed87c11cd89bf15fa90d3",
    "id": "CVE-2026-42559",
    "bulletinFamily": "",
    "cwe": [
        "CWE-346",
        "CWE-350"
    ],
    "cvelist": null,
    "sourceData": "modelcontextprotocol rust-sdk < 1.4.0",
    "sourceHref": "",
    "cvss": {
        "score": 8.8,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
        "version": "3.1"
    },
    "cvss2": [],
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        "baseScore": 0,
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        "privilegesRequired": "",
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        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
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    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "rust-sdk",
    "version": "< 1.4.0",
    "vendor": "modelcontextprotocol",
    "ai_description": "",
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    "ai_score": 0
}