CVE-2026-25536
Unknown Unknown - Not Provided
Cross-Client Data Leak in MCP TypeScript SDK Transport

Publication date: 2026-02-04

Last updated on: 2026-03-18

Assigner: GitHub, Inc.

Description
MCP TypeScript SDK is the official TypeScript SDK for Model Context Protocol servers and clients. From version 1.10.0 to 1.25.3, cross-client response data leak when a single McpServer/Server and transport instance is reused across multiple client connections, most commonly in stateless StreamableHTTPServerTransport deployments. This issue has been patched in version 1.26.0.
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Meta Information
Published
2026-02-04
Last Modified
2026-03-18
Generated
2026-06-16
AI Q&A
2026-02-05
EPSS Evaluated
2026-06-15
NVD
CVE-2026-25536
EUVD
EUVD-2026-5335
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
lfprojects mcp_typescript_sdk From 1.10.0 (inc) to 1.26.0 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-362 The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
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Executive Summary

The vulnerability exists in the MCP TypeScript SDK versions 1.10.0 to 1.25.3. It causes cross-client response data leakage when a single McpServer/Server and transport instance is reused across multiple client connections. This issue is most common in stateless StreamableHTTPServerTransport deployments. The vulnerability has been fixed in version 1.26.0.

Impact Analysis

This vulnerability can lead to unauthorized disclosure of sensitive data between different clients because response data from one client may be leaked to another. This compromises confidentiality and can result in data breaches.

Compliance Impact

I don't know

Detection Guidance

I don't know

Mitigation Strategies

To mitigate this vulnerability, upgrade the MCP TypeScript SDK to version 1.26.0 or later, where the issue has been patched.

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