---
id: CVE-2026-25536
title: >-
  MCP TypeScript SDK is the official TypeScript SDK for Model Context Protocol
  servers and clients
summary: >-
  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
  multi…
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N'
cwe:
  - CWE-362
  - CWE-367
vendor: lfprojects
product: mcp_typescript_sdk
affected:
  - 'mcp_typescript_sdk >= 1.10.0, < 1.26.0'
patched:
  - mcp_typescript_sdk 1.26.0
published: '2026-02-04'
updated: '2026-06-30'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-25536'
references:
  - url: 'https://github.com/modelcontextprotocol/typescript-sdk/issues/204'
    label: security-advisories@github.com
  - url: 'https://github.com/modelcontextprotocol/typescript-sdk/issues/243'
    label: security-advisories@github.com
  - url: >-
      https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-345p-7cg4-v4c7
    label: security-advisories@github.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:3960'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/security/cve/CVE-2026-25536'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2436937'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-25536.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
tags:
  - nvd
epss: 0.00358
epssPercentile: 0.26772
ingestedAt: '2026-07-03T18:53:52.170Z'
---

## Overview

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

- `mcp_typescript_sdk >= 1.10.0, < 1.26.0`

## Remediation

Upgrade past the affected range:

- `mcp_typescript_sdk 1.26.0`