{"id":"CVE-2026-42559","revision":"e638d63a6eff403ba065474a56652790","records":[{"revision":"e638d63a6eff403ba065474a56652790","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-42559","aliases":[],"title":"RMCP: DNS rebinding vulnerability in rmcp Streamable HTTP server transport","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.","state":0,"publishedAt":"2026-05-14T14:24:56.09+00:00","modifiedAt":"2026-05-14T16:00:33.149+00:00","affected":[{"ecosystem":"Vendor product","name":"rust-sdk","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"modelcontextprotocol\",\n                    \"product\": \"rust-sdk\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 1.4.0\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","score":8.8,"severity":"HIGH"}],"references":["https://github.com/modelcontextprotocol/rust-sdk/security/advisories/GHSA-89vp-x53w-74fx","https://github.com/modelcontextprotocol/rust-sdk/issues/815","https://github.com/modelcontextprotocol/rust-sdk/issues/822","https://github.com/modelcontextprotocol/rust-sdk/pull/764","https://github.com/modelcontextprotocol/rust-sdk/commit/8e22aa2de28df5a285eed87c11cd89bf15fa90d3"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-42559","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-42559","identifiers":["CVE-2026-42559"]},"retained":false,"historicalAffected":[]}],"coverage":[]}