{"cve":"CVE-2026-42559","nvd":{"published":"2026-05-14T15:16:46.750","modified":"2026-10-26T14:10:00.130","status":"Deferred","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.","cvss_v4":null,"cvss_v3":{"version":"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},"cwes":["CWE-346","CWE-350"],"references":["https://github.com/modelcontextprotocol/rust-sdk/commit/8e22aa2de28df5a285eed87c11cd89bf15fa90d3","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/security/advisories/GHSA-89vp-x53w-74fx"],"products":[],"source":"nvd","synced_at":"2026-10-26T14:27:29.784594657+00:00"},"epss":{"cve":"CVE-2026-42559","score":0.00269,"percentile":0.1892,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-89vp-x53w-74fx","url":"https://osv.dev/vulnerability/GHSA-89vp-x53w-74fx","summary":"rmcp Streamable HTTP server transport has a DNS rebinding vulnerability","modified":"2026-09-10T03:51:04.771476338Z","packages":[{"ecosystem":"crates.io","name":"rmcp","purl":"pkg:cargo/rmcp","ranges":["<1.4.0"],"fixed":["1.4.0"]}]},{"id":"GHSA-fvh2-gm75-j4j7","url":"https://osv.dev/vulnerability/GHSA-fvh2-gm75-j4j7","summary":"dynoxide: DNS rebinding and cross-origin CSRF via MCP HTTP transport","modified":"2026-06-29T13:14:15.290444787Z","packages":[{"ecosystem":"crates.io","name":"dynoxide-rs","purl":"pkg:cargo/dynoxide-rs","ranges":[">=0.9.3 <0.9.13"],"fixed":["0.9.13"]},{"ecosystem":"npm","name":"dynoxide","purl":"pkg:npm/dynoxide","ranges":[">=0.9.3 <0.9.13"],"fixed":["0.9.13"]}]},{"id":"RUSTSEC-2026-0140","url":"https://osv.dev/vulnerability/RUSTSEC-2026-0140","summary":"DNS rebinding and cross-origin CSRF in dynoxide's MCP HTTP transport","modified":"2026-10-12T18:00:08.330166697Z","packages":[{"ecosystem":"crates.io","name":"dynoxide-rs","purl":"pkg:cargo/dynoxide-rs","ranges":[">=0.9.3 <0.9.13"],"fixed":["0.9.13"]}]},{"id":"RUSTSEC-2026-0189","url":"https://osv.dev/vulnerability/RUSTSEC-2026-0189","summary":"DNS rebinding vulnerability in rmcp Streamable HTTP server transport","modified":"2026-10-12T18:00:14.804412378Z","packages":[{"ecosystem":"crates.io","name":"rmcp","purl":"pkg:cargo/rmcp","ranges":[">=0.0.0-0 <1.4.0"],"fixed":["1.4.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}