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.
- CVSS 3.1
- 7.6
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L - EPSS
- 0.4% chance of exploitation in the next 30 days; higher than 32% of CVEs (scores of 2026-10-25)
- CWE
- CWE-862
- Published
- Modified
- Record from
- the NVD, synced
Affected
- lfprojects:mcp_python_sdk
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-hvrp-rf83-w775 | PyPI | mcp | >=1.23.0 <1.27.2 | 1.27.2 |
| PYSEC-2026-3481 | PyPI | mcp | >=1.23.0 <1.27.2 | 1.27.2 |
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