7.1

CVE-2026-52869

MCP Python SDK: HTTP transports serve session requests without verifying the authenticated principal

The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to 1.27.2, the SSE and stateful Streamable HTTP transports mcp.server.sse.SseServerTransport and mcp.server.streamable_http_manager.StreamableHTTPSessionManager route requests to existing sessions using only the session_id query parameter or Mcp-Session-Id header without verifying the authenticated principal that created the session, allowing a different bearer-token-authenticated client with a known session ID to inject JSON-RPC messages into that session. This issue is fixed in version 1.27.2.
Daten sind bereitgestellt durch National Vulnerability Database (NVD)
Lfprojects ≫ Mcp Python Sdk Version < 1.27.2
Zu dieser CVE wurde keine Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.32% 0.242
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
security-advisories@github.com 7.1 1.6 5.5
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L
CWE-639 Authorization Bypass Through User-Controlled Key

The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.

https://github.com/modelcontextprotocol/python-sdk/commit/1abcca2408a6b50e10ec601181f63f9978705c00
Patch
https://github.com/modelcontextprotocol/python-sdk/commit/ce267b6fc515dc4efc1dc70b6975b16ff0feef0a
Patch
https://github.com/modelcontextprotocol/python-sdk/pull/2690
Patch
Issue Tracking
https://github.com/modelcontextprotocol/python-sdk/pull/2719
Patch
Issue Tracking
https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.27.2
Release Notes
https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-jpw9-pfvf-9f58
Vendor Advisory