CVE-2026-52870CWE-862broken-access-control

CVE-2026-52870

High · published July 16, 2026

CVSS v3.1
7.6
EPSS
0%
Percentile
31.7
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
7.6 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L
CVSS v4.0
Not supplied
EPSS
0.00388 · 31.7th percentile
Weakness
CWE-862 · Missing Authorization
Published
2026-07-16T00:17Z
Affected products (1)
ProductVersionsFixed in
lfprojects/mcp_python_sdk≥ 1.23.0, < 1.27.21.27.2
References (4)
https://github.com/modelcontextprotocol/python-sdk/commit/62137874ff26dd74d2fea80ff528a7fd9ca7a5e7 · [email protected]https://github.com/modelcontextprotocol/python-sdk/pull/2720 · [email protected]https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.27.2 · [email protected]https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-hvrp-rf83-w775 · [email protected]
EPSS history
Timeline
  • 15 JUL 20:07Z
    MCP Python SDK: Experimental task handlers allow any client to access and cancel other clients' tasks
    cvelistv5