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TI-2026-37971 Aliases CVE-2026-52870GHSA-hvrp-rf83-w775

MCP Python SDK: Experimental task handlers allow any client to access and cancel other clients' tasks

Priority LOW 33CWE-862Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
High · Low · Low
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-862.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00388 33rd percentileScored 2026-11-07
Fix Fixed python-sdk (modelcontextprotocol): 1.27.2mcp (PyPI): 1.27.2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
MLflowpython-sdk1.23.0 to before 1.27.21.27.2Patch availableCNA
—mcp (PyPI)1.23.0 to before 1.27.21.27.2Patch availableGHSA-hvrp-rf83-w775
  • python-sdk VendorMLflow Affected 1.23.0 to before 1.27.2 Fixed in 1.27.2 Patch available CNA
  • mcp (PyPI) Vendor— Affected 1.23.0 to before 1.27.2 Fixed in 1.27.2 Patch available GHSA-hvrp-rf83-w775

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:lfprojects:mcp_python_sdk:*:*:*:*:*:*:*:*1.23.0 to before 1.27.2VulnerableMLflow
  • cpe:2.3:a:lfprojects:mcp_python_sdk:*:*:*:*:*:*:*:* Versions 1.23.0 to before 1.27.2 Vulnerable ·MLflow

Remediation

  • Fix · CNA python-sdk (modelcontextprotocol) Fixed in 1.27.2
  • Fix · GHSA-hvrp-rf83-w775 mcp (PyPI) Fixed in 1.27.2 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-52870
  2. 2026-10-03 Alias added: GHSA-hvrp-rf83-w775

References

Patch 2

Advisory 2

Other 2

  • TI-2025-40852 DNS Rebinding Protection Disabled by Default in Model Context Protocol Python SDK for Servers Running on Localhost CVSS 4.0HIGH 7.6
  • TI-2026-42756 MCP Python SDK: WebSocket server transport does not support Host/Origin validation CVSS 4.0HIGH 7.6
  • TI-2026-37970 MCP Python SDK: HTTP transports serve session requests without verifying the authenticated principal CVSS 3.1HIGH 7.1

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences