{"id":"CVE-2026-59950","summary":"MCP Python SDK: WebSocket server transport does not support Host/Origin validation","details":"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.","aliases":["GHSA-vj7q-gjh5-988w"],"modified":"2026-07-19T03:47:17.288633252Z","published":"2026-07-15T20:08:54.095Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-1385","CWE-346"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59950.json"},"references":[{"type":"WEB","url":"https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59950.json"},{"type":"ADVISORY","url":"https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7q-gjh5-988w"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59950"},{"type":"FIX","url":"https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266"},{"type":"FIX","url":"https://github.com/modelcontextprotocol/python-sdk/pull/2992"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/modelcontextprotocol/python-sdk","events":[{"introduced":"0"},{"fixed":"777b8d06710c140e3606b0d4598e2aa48546c266"}],"database_specific":{"source":["AFFECTED_FIELD","CPE_RANGE","REFERENCES"],"cpe":"cpe:2.3:a:lfprojects:mcp_python_sdk:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"fixed":"1.28.1"}]}}],"versions":["v1.28.0","v1.27.2","v1.27.1","v1.27.0","v1.26.0","v1.25.0","v1.24.0","v1.23.3","v1.23.2","v1.23.1","v1.23.0","v1.22.0","v1.21.1","v1.21.0","v1.20.0","v1.19.0","v1.18.0","v1.17.0","v1.16.0","v1.15.0","1.15.0","v1.14.1","v1.14.0","v1.13.1","v1.13.0","v1.12.4","v1.12.3","v1.12.2","v1.12.1","v1.12.0","v1.11.0","v1.10.1","v1.10.0","v1.9.4","v1.9.3","v1.9.2","v1.9.1","v1.9.0","v1.8.1","v1.8.0","v1.7.0","v1.6.0","v1.5.0","v1.4.1","v1.4.0","v1.0.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-59950.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"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"}]}