CVE-2026-52870
MCP Python SDK: Experimental task handlers allow any client to access and cancel other clients' tasks
Description
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.
INFO
Published Date :
July 15, 2026, 8:17 p.m.
Last Modified :
July 17, 2026, 6:07 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update the MCP Python SDK to version 1.27.2 or later.
- Ensure tasks are properly authorized before execution.
Public PoC/Exploit Available at Github
CVE-2026-52870 has a 2 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-52870.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-52870 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-52870
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
The Project shares all information on MCP related CVE's published
mcp mcp-security mcp-cve
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Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-52870 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-52870 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jul. 17, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:lfprojects:mcp_python_sdk:*:*:*:*:*:*:*:* versions from (including) 1.23.0 up to (excluding) 1.27.2 Added Reference Type GitHub, Inc.: https://github.com/modelcontextprotocol/python-sdk/commit/62137874ff26dd74d2fea80ff528a7fd9ca7a5e7 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/modelcontextprotocol/python-sdk/pull/2720 Types: Issue Tracking, Patch Added Reference Type GitHub, Inc.: https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.27.2 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-hvrp-rf83-w775 Types: Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 16, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-52870', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-16T13:01:33.294977Z'} -
New CVE Received by [email protected]
Jul. 15, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'modelcontextprotocol', 'product': 'python-sdk', 'versions': [{'status': 'affected', 'version': '>= 1.23.0, < 1.27.2'}]}] Added Description 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. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L Added CWE CWE-862 Added Reference https://github.com/modelcontextprotocol/python-sdk/commit/62137874ff26dd74d2fea80ff528a7fd9ca7a5e7 Added Reference https://github.com/modelcontextprotocol/python-sdk/pull/2720 Added Reference https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.27.2 Added Reference https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-hvrp-rf83-w775