CVE-2026-59950The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP).
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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
- 8.1 HIGH (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
- Weakness (CWE)
- CWE-346, CWE-1385
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Analyzed
- Record last updated
- Jul 17, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
lfprojects mcp_python_sdk lfprojects:mcp_python_sdk | before 1.28.1 | NVD |
References
- https://github.com/modelcontextprotocol/python-sdk/commit/777b8d06710c140e3606b0d4598e2aa48546c266patch
- https://github.com/modelcontextprotocol/python-sdk/pull/2992issue-tracking, patch
- https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.28.1release-notes
- https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-vj7q-gjh5-988wvendor-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.