PYSEC-2026-3481 MCP Python SDK: Experimental task handlers allow any client to access and cancel other clients' tasks

Summary In affected versions, the default request handlers installed by the experimental tasks feature server.experimental.enabletasks did not check which session created a task before acting on it. On a server with more than one connected client, any client could observe, read results from, and...

GHSA-HVRP-RF83-W775 MCP Python SDK: Experimental task handlers allow any client to access and cancel other clients' tasks

Summary In affected versions, the default request handlers installed by the experimental tasks feature server.experimental.enabletasks did not check which session created a task before acting on it. On a server with more than one connected client, any client could observe, read results from, and...

CVE-2026-52870

The MCP Python SDK (package mcp on PyPI) has a vulnerability in versions 1.23.0–1.27.1 where default handlers installed by server.experimental.enable_tasks() for tasks/list, tasks/get, tasks/result, and tasks/cancel only operate on task identifiers and do not record the session that created each ...