CVE-2026-599507.6HighCWE-1385

CVE-2026-59950: MCP Python SDK: WebSocket server transport does not support Host/Origin validation

modelcontextprotocol · python-sdk

Affected: modelcontextprotocol python-sdk · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.2%probability of exploitation in the next 30 days

14th percentile

050100

Higher than 14% of scored CVEs

7.6HighCVSS 4.0

LowMediumHighCrit.

DescriptionCVE.org

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 products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

modelcontextprotocol · python-sdk< 1.28.1

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Missing Origin Validation in WebSockets · Access Control
Vendor: modelcontextprotocol
Published: July 2026
Band: Unlikely (under 1%), July 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-59950 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.