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Details of issue NIXPKGS-2026-2298

NIXPKGS-2026-2298
published 3 hours ago
MCP Python SDK: Experimental task handlers allow any client to access and cancel other clients' tasks
Permalink CVE-2026-52870
7.6 HIGH
  • CVSS version (CVSS): 3.1
  • Attack Vector (AV): Network (N)
  • Attack Complexity (AC): Low (L)
  • Privileges Required (PR): Low (L)
  • User Interaction (UI): None (N)
  • Scope (S): Unchanged (U)
  • Confidentiality (C): High (H)
  • Integrity (I): Low (L)
  • Availability (A): Low (L)
  • Modified Attack Vector (MAV): Network (N)
  • Modified Attack Complexity (MAC): Low (L)
  • Modified Privileges Required (MPR): Low (L)
  • Modified User Interaction (MUI): None (N)
  • Modified Confidentiality (MC): High (H)
  • Modified Scope (MS): Unchanged (U)
  • Modified Integrity (MI): Low (L)
  • Modified Availability (MA): Low (L)
updated 3 hours ago by @erictapen Activity log
  • Created suggestion 1 week, 1 day ago
  • @erictapen ignored
    18 packages
    • python314Packages.aliyun-python-sdk-config
    • python313Packages.aliyun-python-sdk-config
    • python314Packages.aliyun-python-sdk-alimt
    • python313Packages.aliyun-python-sdk-alimt
    • python314Packages.aliyun-python-sdk-dbfs
    • python314Packages.aliyun-python-sdk-core
    • python313Packages.aliyun-python-sdk-dbfs
    • python313Packages.aliyun-python-sdk-core
    • python314Packages.aliyun-python-sdk-sts
    • python314Packages.aliyun-python-sdk-kms
    • python314Packages.aliyun-python-sdk-iot
    • python314Packages.aliyun-python-sdk-cdn
    • python313Packages.aliyun-python-sdk-sts
    • python313Packages.aliyun-python-sdk-kms
    • python313Packages.aliyun-python-sdk-iot
    • python313Packages.aliyun-python-sdk-cdn
    • python314Packages.bce-python-sdk
    • python313Packages.bce-python-sdk
    3 hours ago
  • @erictapen accepted 3 hours ago
  • @erictapen published on GitHub 3 hours ago
MCP Python SDK: Experimental task handlers allow any client to access and cancel other clients' tasks

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 products

python-sdk
  • ==>= 1.23.0, < 1.27.2
Ignored packages (18) 
Affects python3Packages.mcp