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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
Low
Partial data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
References 3
https://github.com/modelcontextprotocol/typescript-sdk/issues/204
security-advisories@github.com
https://github.com/modelcontextprotocol/typescript-sdk/issues/243
security-advisories@github.com
https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA…
security-advisories@github.com