CVE-2026-59950

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Source
https://cve.org/CVERecord?id=CVE-2026-59950
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-59950.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-59950
Aliases
Downstream
CGA (7)
CLEANSTART (1)
ECHO (1)
MINI (18)
ROOT (1)
Published
2026-07-15T20:08:54Z
Modified
2026-10-28T02:31:11Z
Severity
  • 7.6 (High) CVSS_V4 - 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 CVSS Calculator
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.

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

Affected packages

Git / github.com/modelcontextprotocol/python-sdk

Affected ranges

Type
GIT
Repo
https://github.com/modelcontextprotocol/python-sdk
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
777b8d06710c140e3606b0d4598e2aa48546c266
Database specific
Show details 
{
    "extracted_events": [
        {
            "range": [
                {
                    "introduced": "0"
                },
                {
                    "fixed": "1.28.1"
                }
            ],
            "source": "AFFECTED_FIELD",
            "strategy": "StringRangeExpression"
        },
        {
            "range": [
                {
                    "fixed": "777b8d06710c140e3606b0d4598e2aa48546c266"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "original_tag": "v1.28.1",
            "range": [
                {
                    "fixed": "777b8d06710c140e3606b0d4598e2aa48546c266"
                }
            ],
            "source": "REFERENCES_TAG"
        },
        {
            "cpe": "cpe:2.3:a:lfprojects:mcp_python_sdk:*:*:*:*:*:*:*:*",
            "range": [
                {
                    "introduced": "0"
                },
                {
                    "fixed": "1.28.1"
                }
            ],
            "source": "CPE_RANGE"
        }
    ]
}

Affected versions

1.*
1.15.0
v1.*
v1.0.0
v1.10.0
v1.10.1
v1.11.0
v1.12.0
v1.12.1
v1.12.2
v1.12.3
v1.12.4
v1.13.0
v1.13.1
v1.14.0
v1.14.1
v1.15.0
v1.16.0
v1.17.0
v1.18.0
v1.19.0
v1.20.0
v1.21.0
v1.21.1
v1.22.0
v1.23.0
v1.23.1
v1.23.2
v1.23.3
v1.24.0
v1.25.0
v1.26.0
v1.27.0
v1.27.1
v1.27.2
v1.28.0
v1.4.0
v1.4.1
v1.5.0
v1.6.0
v1.7.0
v1.8.0
v1.8.1
v1.9.0
v1.9.1
v1.9.2
v1.9.3
v1.9.4

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-59950.json"