CVE-2026-111767
Deferred Deferred - Pending Action

Session Task Privilege Escalation in MCP TypeScript SDK

Publication date: 2026-10-20

Last updated on: 2026-10-20

Assigner: GitHub, Inc.

Description
MCP TypeScript SDK is the official TypeScript SDK for Model Context Protocol servers and clients. From version 1.24.0 to before version 1.32.0, the experimental tasks feature (taskStore) did not check which session created a task. Clients sharing one InMemoryTaskStore could list, read and cancel each other's tasks. This issue has been patched in version 1.32.0.

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Meta Information

Published
2026-10-20
Last Modified
2026-10-20
Generated
2026-10-22
AI Q&A
2026-10-21
EPSS Evaluated
N/A
NVD
CVE-2026-111767
EUVD
EUVD-2026-105256

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
modelcontextprotocol typescript-sdk >= 1.24.0, < 1.32.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-639 The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
CWE-862 The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

Attack-Flow Graph

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Executive Summary

This vulnerability affects the MCP TypeScript SDK's experimental tasks feature between versions 1.24.0 and 1.31.0. Tasks stored in the InMemoryTaskStore were not properly scoped to the session that created them, allowing clients sharing the same store to list, read, and cancel each other's tasks without authorization.

Detection Guidance

To detect this vulnerability, check if your MCP TypeScript SDK version is between 1.24.0 and 1.31.0. Run: npm list @modelcontextprotocol/sdk. If the version is vulnerable, upgrade to 1.32.0 or later.

Impact Analysis

An attacker sharing the same InMemoryTaskStore could access, modify, or cancel tasks belonging to other users. This could lead to unauthorized data exposure, task manipulation, or disruption of services relying on the MCP SDK.

Compliance Impact

This vulnerability could violate data protection requirements by allowing unauthorized access to sensitive task data. GDPR requires protecting personal data, and HIPAA requires safeguarding protected health information. Unauthorized task access may lead to compliance breaches.

Mitigation Strategies
  • Upgrade to MCP TypeScript SDK version 1.32.0 or later to apply the session-based task isolation fix.
  • If upgrading is not possible, remove the taskStore or create a separate InMemoryTaskStore per session to prevent cross-session task access.
  • Review and update any custom TaskStore implementations to include session-based access control similar to the patched version.

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