Vulnerability Details CVE-2026-52870
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.002
EPSS Ranking 12.9%
CVSS Severity
CVSS v3 Score 7.6
References
- https://github.com/modelcontextprotocol/python-sdk/commit/62137874ff26dd74d2fea80ff528a7fd9ca7a5e7
- https://github.com/modelcontextprotocol/python-sdk/pull/2720
- https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.27.2
- https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-hvrp-rf83-w775
Products affected by CVE-2026-52870
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cpe:2.3:a:lfprojects:mcp_python_sdk:1.23.0
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cpe:2.3:a:lfprojects:mcp_python_sdk:1.23.1
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cpe:2.3:a:lfprojects:mcp_python_sdk:1.23.2
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cpe:2.3:a:lfprojects:mcp_python_sdk:1.23.3
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cpe:2.3:a:lfprojects:mcp_python_sdk:1.24.0
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cpe:2.3:a:lfprojects:mcp_python_sdk:1.25.0
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cpe:2.3:a:lfprojects:mcp_python_sdk:1.26.0
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cpe:2.3:a:lfprojects:mcp_python_sdk:1.27.0
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cpe:2.3:a:lfprojects:mcp_python_sdk:1.27.1