CVE-2026-52870 | The MCP Python SDK, called mcp on PyPI, is a Python implemen… | CVSS 7.6 HIGH

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.

Metadata

CVE ID: CVE-2026-52870
State: PUBLISHED
Assigner: GitHub_M
Reserved: 2026-06-08 21:44 UTC
Published: 2026-07-15 20:07 UTC
Last updated: 2026-07-16 13:01 UTC
Primary CWE: CWE-862
CWE-862: Missing Authorization
Vendor / Product: modelcontextprotocol / python-sdk
Sources: cve.org · NVD

Severity & Metrics

7.6 HIGH CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L

SSVC — CISA Coordinator

Exploitation: none
Automatable: no
Tech. Impact: partial

Affected products (1)

Vendor	Product	Platform	Versions
modelcontextprotocol	python-sdk	—	>= 1.23.0, < 1.27.2

Weakness (CWE)

CWE	Source	Description
CWE-862	cna	CWE-862: Missing Authorization

CVSS scores (1)

Score	Severity	Version	Source	Vector
7.6	HIGH	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L

References (4)

https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-hvrp-rf83-w775 https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-hvrp-rf83-w775
https://github.com/modelcontextprotocol/python-sdk/pull/2720 https://github.com/modelcontextprotocol/python-sdk/pull/2720
https://github.com/modelcontextprotocol/python-sdk/commit/62137874ff26dd74d2fea80ff528a7fd9ca7a5e7 https://github.com/modelcontextprotocol/python-sdk/commit/62137874ff26dd74d2fea80ff528a7fd9ca7a5e7
https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.27.2 https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.27.2