CVE-2026-52870

What it is

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.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of data exposure.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-07-15 20:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-24 21:10 UTC Last updatedMost recent change to the record

Details

Published

2026-07-15 20:17 UTC

Last modified

2026-10-24 21:10 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-862 · Missing authorization

Record status

Analyzed

Affected

• Lfprojects Mcp Python Sdk < 1.27.2

Attack profile CVSS 3.1 · 7.6

Attack vector

Network

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

Low

Availability

Low