2026-02-04 · 2026-Q1
MCP TypeScript SDK Cross-Client Data Leak
PrimaryL6Identity / Run
- Fixable:
- Yes, vendor patch
- Vendor response:
- Patched
- In the wild:
- No
- Actor:
- Attacker
Target
MCP TypeScript SDK (v1.10.0-1.25.3)
Impact
Tool results, resource content, and error messages routed to wrong client in multi-tenant deployments
Root Cause
Race condition in response multiplexing of StreamableHTTPServerTransport