CVE-2026-25536 HIGH

CVE-2026-25536: @modelcontextprotocol/sdk has cross-client data leak via shared server/transport instance reuse

Vendor Modelcontextprotocol
Product typescript-sdk
Weakness CWE-362
Published February 4, 2026
Last update June 30, 2026
View on NVD All CVEs

CVSS base score

7.1/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality High
Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

February 4, 2026 CVE published
June 30, 2026 Record updated