CVE-2026-52870

HIGH

MEDIUM Priority: 0.03 BB Relevance: 65/100

Published: 2026-07-15 Modified: 2026-10-24 First seen: 2026-10-29 Status: active

Attack Surface

Network Low Complexity No Interaction Conf. Impact

CVSS Vector Breakdown

AV: Network

AC: Low

PR: Low

UI: None

S: Unchanged

C: High

I: Low

A: Low

Description

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.