CVE-2026-52870: CWE-862: Missing Authorization in modelcontextprotocol python-sdk
A missing authorization vulnerability exists in the MCP Python SDK (modelcontextprotocol) versions from 1.23.0 up to but not including 1.27.2. Default handlers for task operations do not associate tasks with the creating session, allowing any connected client to enumerate, read, consume, or cancel tasks belonging to other clients. This issue is fixed in version 1.27.2.
AI Analysis
Technical Summary
The MCP Python SDK (modelcontextprotocol) versions >=1.23.0 and <1.27.2 contain a missing authorization vulnerability (CWE-862) in default handlers installed by server.experimental.enable_tasks(). These handlers for tasks/list, tasks/get, tasks/result, and tasks/cancel operate solely on task identifiers without tracking the session that created each task. As a result, any connected client can access or manipulate tasks created by other clients. The vulnerability is addressed in version 1.27.2.
Potential Impact
An attacker with access to the MCP Python SDK server can enumerate other clients' tasks, read their results, consume their messages, or cancel their tasks. This leads to unauthorized disclosure of task data, partial integrity loss, and availability impact on other clients' tasks. The CVSS 3.1 base score is 7.6 (High), reflecting network attack vector, low attack complexity, required privileges, no user interaction, unchanged scope, high confidentiality impact, low integrity impact, and low availability impact.
Mitigation Recommendations
Upgrade to MCP Python SDK version 1.27.2 or later, where this missing authorization vulnerability is fixed. No other mitigation or temporary workaround is indicated in the available data.
CVE-2026-52870: CWE-862: Missing Authorization in modelcontextprotocol python-sdk
Description
A missing authorization vulnerability exists in the MCP Python SDK (modelcontextprotocol) versions from 1.23.0 up to but not including 1.27.2. Default handlers for task operations do not associate tasks with the creating session, allowing any connected client to enumerate, read, consume, or cancel tasks belonging to other clients. This issue is fixed in version 1.27.2.
CVSS v3.1
Score 7.6high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The MCP Python SDK (modelcontextprotocol) versions >=1.23.0 and <1.27.2 contain a missing authorization vulnerability (CWE-862) in default handlers installed by server.experimental.enable_tasks(). These handlers for tasks/list, tasks/get, tasks/result, and tasks/cancel operate solely on task identifiers without tracking the session that created each task. As a result, any connected client can access or manipulate tasks created by other clients. The vulnerability is addressed in version 1.27.2.
Potential Impact
An attacker with access to the MCP Python SDK server can enumerate other clients' tasks, read their results, consume their messages, or cancel their tasks. This leads to unauthorized disclosure of task data, partial integrity loss, and availability impact on other clients' tasks. The CVSS 3.1 base score is 7.6 (High), reflecting network attack vector, low attack complexity, required privileges, no user interaction, unchanged scope, high confidentiality impact, low integrity impact, and low availability impact.
Mitigation Recommendations
Upgrade to MCP Python SDK version 1.27.2 or later, where this missing authorization vulnerability is fixed. No other mitigation or temporary workaround is indicated in the available data.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-08T21:44:27.364Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a57eb0d68715ace4363c934
Added to database: 07/15/2026, 20:18:21 UTC
Last enriched: 07/22/2026, 23:03:16 UTC
Last updated: 08/29/2026, 10:52:09 UTC
Views: 125
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