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

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...

GHSA-345P-7CG4-V4C7 @modelcontextprotocol/sdk has cross-client data leak via shared server/transport instance reuse

Summary Cross-client data leak via two distinct issues: 1 reusing a single StreamableHTTPServerTransport across multiple client requests, and 2 reusing a single McpServer/Server instance across multiple transports. Both are most common in stateless deployments. Impact This advisory covers two...

PT-2026-6315

Name of the Vulnerable Software and Affected Versions MCP TypeScript SDK versions 1.10.0 through 1.25.3 Description The MCP TypeScript SDK, designed for Model Context Protocol servers and clients, exhibits a cross-client response data leak. This occurs when a single McpServer/Server and transport...