CVE-2026-25536
February 04, 2026
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.
Affected Packages
https://github.com/modelcontextprotocol/typescript-sdk.git (GITHUB):
Affected version(s) >=v1.25.2 <v1.26.0Fix Suggestion:
Update to version v1.26.0@modelcontextprotocol/sdk (NPM):
Affected version(s) >=1.10.0 <1.26.0Fix Suggestion:
Update to version 1.26.0Related Resources (5)
Do you need more information?
Contact UsCVSS v4
Base Score:
7.1
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
NONE
Vulnerable System Confidentiality
HIGH
Vulnerable System Integrity
LOW
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.1
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
LOW
Availability
NONE
Weakness Type (CWE)
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
EPSS
Base Score:
0.01
