CVE-2026-52870
Published:July 15, 2026
Updated:July 30, 2026
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.
Affected Packages
mcp (CONDA):
Affected version(s) >=1.23.1 <1.27.2Fix Suggestion:
Update to version 1.27.2https://github.com/modelcontextprotocol/python-sdk.git (GITHUB):
Affected version(s) >=v1.23.0 <v1.27.2Fix Suggestion:
Update to version v1.27.2mcp (PYTHON):
Affected version(s) >=1.23.0 <1.27.2Fix Suggestion:
Update to version 1.27.2Related Resources (9)
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Contact UsCVSS v4
Base Score:
7.2
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
NONE
Vulnerable System Confidentiality
HIGH
Vulnerable System Integrity
LOW
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.6
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
LOW
Availability
LOW
Weakness Type (CWE)
Missing Authorization
EPSS
Base Score:
0.24