CVE-2026-52870
MCP Python SDK: Experimental task handlers allow any client to access and cancel other clients' tasks
CVSS Score
7.6
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-862 |
| Vendor | modelcontextprotocol |
| Product | python-sdk |
| Published | Jul 15, 2026 |
| Last Updated | Jul 16, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
Low
Affected Versions
modelcontextprotocol / python-sdk
>= 1.23.0, < 1.27.2
References
github.com: https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-hvrp-rf83-w775 github.com: https://github.com/modelcontextprotocol/python-sdk/pull/2720 github.com: https://github.com/modelcontextprotocol/python-sdk/commit/62137874ff26dd74d2fea80ff528a7fd9ca7a5e7 github.com: https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.27.2