CVE-2026-25536
Cross-Client Data Leak in MCP TypeScript SDK Transport
Publication date: 2026-02-04
Last updated on: 2026-03-18
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| lfprojects | mcp_typescript_sdk | From 1.10.0 (inc) to 1.26.0 (exc) |
Helpful Resources
Exploitability
| 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. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
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.
How can this vulnerability impact me? :
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.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, upgrade the MCP TypeScript SDK to version 1.26.0 or later, where the issue has been patched.