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CVE-2026-52870— MCP Python SDK: Experimental task handlers allow any client to access and cancel other clients' tasks

CVSS 7.6 · High EPSS 0.22% · P13

Affected Version Matrix 1

VendorProductVersion RangeStatus
modelcontextprotocolpython-sdk>= 1.23.0, < 1.27.2affected
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I. Basic Information for CVE-2026-52870

Vulnerability Information
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Vulnerability Title
MCP Python SDK: Experimental task handlers allow any client to access and cancel other clients' tasks
Source: NVD (National Vulnerability Database)
Vulnerability 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.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L
Source: NVD (National Vulnerability Database)
Vulnerability Type
授权机制缺失
Source: NVD (National Vulnerability Database)
Vulnerability Title
Model Context Protocol MCP Python SDK 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Model Context Protocol MCP Python SDK是Model Context Protocol组织的一款Python软件开发工具包。 Model Context Protocol MCP Python SDK 1.23.0版本及之后至1.27.2之前版本存在授权问题漏洞，该漏洞源于server.experimental.enable_tasks()安装的默认处理程序仅操作任务标识符而不记录创建每个任务的会话，可能导致任何连接的客户端枚举、读取结果、消费消息或取消其他客户端任务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

VendorProductAffected VersionsCPESubscribe
modelcontextprotocolpython-sdk >= 1.23.0, < 1.27.2 -

II. Public POCs for CVE-2026-52870

#POC DescriptionSource LinkShenlong Link
AI-Generated POCPremium
Qwen3.6-35B-A3B · 11123 chars
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III. Intelligence Information for CVE-2026-52870

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Patches & Fixes for CVE-2026-52870 (1)

Vendor Advisories for CVE-2026-52870 (1)

Vendor Pages for CVE-2026-52870 (1)

Same Patch Batch · modelcontextprotocol · 2026-07-15 · 3 CVEs total

CVE-2026-528697.1 HIGHMCP Python SDK: HTTP transports serve session requests without verifying the authenticated
CVE-2026-59950MCP Python SDK: WebSocket server transport does not support Host/Origin validation

IV. Related Vulnerabilities

Same product: python-sdk
Same vendor: modelcontextprotocol
Same weakness: CWE-862

V. Comments for CVE-2026-52870

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