CVE-2026-52870

The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol (MCP). From 1.23.0 until 1.27.2, default handlers installed by server.experimental.enable_tasks() for tasks/list, tasks/get, tasks/result, and tasks/cancel operate only on task identifiers without recording the session that created each task, allowing any connected client to enumerate, read results from, consume messages for, or cancel other clients' tasks. This issue is fixed in version 1.27.2.

• CWE-862

• https://github.com/modelcontextprotocol/python-sdk/commit/62137874ff26dd74d2fea80ff528a7fd9ca7a5e7Patch
• https://github.com/modelcontextprotocol/python-sdk/pull/2720Issue Tracking, Patch
• https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.27.2Release Notes
• https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-hvrp-rf83-w775Vendor Advisory

Published

Jul 15, 2026

Last Modified

Jul 17, 2026

Status

Analyzed

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