{"id":"CVE-2026-59950","state":"PUBLISHED","title":"MCP Python SDK: WebSocket server transport does not support Host/Origin validation","description":"The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to 1.28.1, the deprecated mcp.server.websocket.websocket_server transport accepted WebSocket handshakes without applying Host or Origin header validation, leaving no SDK-level way to restrict which origins could connect to applications that exposed that transport. This issue is fixed in version 1.28.1.","publishedAt":"2026-07-15T20:08:54.095Z","updatedAt":"2026-07-17T12:28:19.431Z","severity":{"score":7.6,"label":"High","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["modelcontextprotocol python-sdk"],"affected":[{"vendor":"modelcontextprotocol","product":"python-sdk","versions":[{"version":"< 1.28.1","status":"affected"}]}],"references":["https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7q-gjh5-988w","https://github.com/modelcontextprotocol/python-sdk/pull/2992","https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266","https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1"],"weaknesses":["CWE-346","CWE-1385"],"ingestedAt":"2026-10-29T20:12:32.778Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/59xxx/CVE-2026-59950.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-59950","state":"PUBLISHED","datePublished":"2026-07-15T20:08:54.095Z","dateUpdated":"2026-07-17T12:28:19.431Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-07-07T18:49:15.607Z"},"containers":{"cna":{"title":"MCP Python SDK: WebSocket server transport does not support Host/Origin validation","descriptions":[{"lang":"en","value":"The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to 1.28.1, the deprecated mcp.server.websocket.websocket_server transport accepted WebSocket handshakes without applying Host or Origin header validation, leaving no SDK-level way to restrict which origins could connect to applications that exposed that transport. This issue is fixed in version 1.28.1."}],"affected":[{"vendor":"modelcontextprotocol","product":"python-sdk","versions":[{"version":"< 1.28.1","status":"affected"}]}],"references":[{"url":"https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7q-gjh5-988w","name":"https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7q-gjh5-988w","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/modelcontextprotocol/python-sdk/pull/2992","name":"https://github.com/modelcontextprotocol/python-sdk/pull/2992","tags":["x_refsource_MISC"]},{"url":"https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266","name":"https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266","tags":["x_refsource_MISC"]},{"url":"https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1","name":"https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"PASSIVE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":7.6,"baseSeverity":"HIGH","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-346","lang":"en","description":"CWE-346: Origin Validation Error","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-1385","lang":"en","description":"CWE-1385: Missing Origin Validation in WebSockets","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-07-15T20:08:54.095Z"},"source":{"advisory":"GHSA-vj7q-gjh5-988w","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-17T12:28:09.718600Z","id":"CVE-2026-59950","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-17T12:28:19.431Z"}}]}}}