CVE-2026-42559

{"id": "CVE-2026-42559", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 8.8, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "REQUIRED", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 2.8}]}, "published": "2026-05-14T15:16:46.750", "references": [{"url": "https://github.com/modelcontextprotocol/rust-sdk/commit/8e22aa2de28df5a285eed87c11cd89bf15fa90d3", "source": "security-advisories@github.com"}, {"url": "https://github.com/modelcontextprotocol/rust-sdk/issues/815", "source": "security-advisories@github.com"}, {"url": "https://github.com/modelcontextprotocol/rust-sdk/issues/822", "source": "security-advisories@github.com"}, {"url": "https://github.com/modelcontextprotocol/rust-sdk/pull/764", "source": "security-advisories@github.com"}, {"url": "https://github.com/modelcontextprotocol/rust-sdk/security/advisories/GHSA-89vp-x53w-74fx", "source": "security-advisories@github.com"}], "vulnStatus": "Deferred", "weaknesses": [{"type": "Primary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-346"}, {"lang": "en", "value": "CWE-350"}]}], "descriptions": [{"lang": "en", "value": "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."}], "lastModified": "2026-05-14T17:19:49.973", "sourceIdentifier": "security-advisories@github.com"}