CVE-2026-111767: @modelcontextprotocol/sdk - Session Mismanagement in Experimental Tasks
Summary
CVE-2026-111767: MCP TypeScript SDK: Experimental tasks were not tied to the session that created them. Affects @modelcontextprotocol/sdk versions >= 1.24.0, < 1.32.0. Fixed in 1.32.0. How to fix ↓
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Background
The @modelcontextprotocol/sdk is a TypeScript SDK designed for managing model context protocols. It allows developers to create and manage tasks within a session. However, the SDK's experimental tasks feature has a significant flaw where tasks are not tied to the session that created them, leading to potential unauthorized access between clients sharing the same task store.
Vulnerability Detail
The vulnerability arises from the experimental tasks feature, specifically the taskStore, which fails to verify the session that initiated a task. This oversight allows clients sharing a single InMemoryTaskStore to list, read, and cancel each other's tasks, posing a risk of data exposure and manipulation. The issue is particularly critical as it undermines session isolation, which is essential for maintaining security in multi-client environments. The vulnerability is classified with a CVSS score of 8.6, indicating a high severity level.
How To Fix
Minimum fixed version
1.32.0
This is the first release that contains the fix.
npm install @modelcontextprotocol/sdk@1.32.0Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
If upgrading is not immediately possible, consider removing the taskStore from your implementation or creating a separate InMemoryTaskStore for each session to mitigate the risk of task sharing. This can be done by instantiating a new InMemoryTaskStore for each user session, ensuring that tasks remain isolated.
Conclusion
The vulnerability CVE-2026-111767 in the @modelcontextprotocol/sdk poses a significant risk due to improper session management in its experimental tasks feature. It is crucial to upgrade to the patched version or implement workarounds to ensure the security of your application.
See every vulnerability recorded for @modelcontextprotocol/sdk →
FAQ
CVE-2026-111767 is a vulnerability in the @modelcontextprotocol/sdk that allows clients to access each other's experimental tasks due to improper session management.
You can check if your application is affected by searching for 'taskStore' in your codebase. If you find no instances, you are not affected.
If you cannot upgrade, you should remove the taskStore or create a separate InMemoryTaskStore for each session to prevent task sharing.
Experimental tasks are a feature in the SDK that allows for task management but are deprecated and replaced by a redesigned extension in the latest specifications.
Vulert monitors and alerts for open-source vulnerabilities in your software using just the package-lock.json file, providing real-time insights without requiring code access.
References
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