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.
Published: 2026-07-15
Score: 7.6 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
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Remediation

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History

Thu, 16 Jul 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 16 Jul 2026 00:00:00 +0000

Type Values Removed Values Added
First Time appeared Modelcontextprotocol
Modelcontextprotocol python-sdk
Vendors & Products Modelcontextprotocol
Modelcontextprotocol python-sdk

Wed, 15 Jul 2026 20:15:00 +0000

Type Values Removed Values Added
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.
Title MCP Python SDK: Experimental task handlers allow any client to access and cancel other clients' tasks
Weaknesses CWE-862
References
Metrics cvssV3_1

{'score': 7.6, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L'}


Subscriptions

Modelcontextprotocol Python-sdk
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-07-16T13:01:40.089Z

Reserved: 2026-06-08T21:44:27.364Z

Link: CVE-2026-52870

cve-icon Vulnrichment

Updated: 2026-07-16T13:01:36.781Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-07-15T23:45:15Z

Weaknesses