{"cve":"CVE-2026-59950","nvd":{"published":"2026-07-15T21:16:55.683","modified":"2026-10-24T21:10:00.130","status":"Analyzed","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.","cvss_v4":{"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","score":7.6},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","score":8.1},"cwes":["CWE-346","CWE-1385"],"references":["https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266","https://github.com/modelcontextprotocol/python-sdk/pull/2992","https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1","https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7q-gjh5-988w"],"products":["lfprojects:mcp_python_sdk"],"source":"nvd","synced_at":"2026-10-25T17:50:08.599881581+00:00"},"epss":{"cve":"CVE-2026-59950","score":0.00231,"percentile":0.13778,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-vj7q-gjh5-988w","url":"https://osv.dev/vulnerability/GHSA-vj7q-gjh5-988w","summary":"MCP Python SDK: WebSocket server transport does not support Host/Origin validation","modified":"2026-09-10T03:50:53.083568399Z","packages":[{"ecosystem":"PyPI","name":"mcp","purl":"pkg:pypi/mcp","ranges":["<1.28.1"],"fixed":["1.28.1"]}]},{"id":"PYSEC-2026-3483","url":"https://osv.dev/vulnerability/PYSEC-2026-3483","summary":"MCP Python SDK: WebSocket server transport does not support Host/Origin validation","modified":"2026-07-23T15:00:13.898863418Z","packages":[{"ecosystem":"PyPI","name":"mcp","purl":"pkg:pypi/mcp","ranges":["<1.28.1"],"fixed":["1.28.1"]}]}],"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."]}