CVE-2026-52870

HIGH7.6

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

Published Jul 15, 2026

Modified 3 months ago

Details

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.

References

WEB

https://github.com/modelcontextprotocol/python-sdk/commit/62137874ff26dd74d2fea80ff528a7fd9ca7a5e7

WEB

https://github.com/modelcontextprotocol/python-sdk/pull/2720

WEB

https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.27.2

WEB

https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-hvrp-rf83-w775

ADVISORY

https://www.cve.org/CVERecord?id=CVE-2026-52870

CVSS Analysis