CVE-2026-25536
@modelcontextprotocol/sdk has cross-client data leak via shared server/transport instance reuse
Description
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.
INFO
Published Date :
Feb. 4, 2026, 10:15 p.m.
Last Modified :
March 18, 2026, 2:22 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update the MCP TypeScript SDK to version 1.26.0.
- Avoid reusing transport instances across client connections.
Public PoC/Exploit Available at Github
CVE-2026-25536 has a 18 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-25536.
| URL | Resource |
|---|---|
| https://github.com/modelcontextprotocol/typescript-sdk/issues/204 | Issue Tracking Vendor Advisory |
| https://github.com/modelcontextprotocol/typescript-sdk/issues/243 | Issue Tracking Vendor Advisory |
| https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-345p-7cg4-v4c7 | Mitigation Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-25536 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-25536
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
None
Shell TypeScript JavaScript Python
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Shell TypeScript JavaScript Python
The Project shares all information on MCP related CVE's published
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A curated timeline of real AI agent security incidents, breaches, and vulnerabilities (2024-2026). Every entry sourced and dated.
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Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-25536 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-25536 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Mar. 18, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:lfprojects:mcp_typescript_sdk:*:*:*:*:*:*:*:* versions from (including) 1.10.0 up to (excluding) 1.26.0 Added Reference Type GitHub, Inc.: https://github.com/modelcontextprotocol/typescript-sdk/issues/204 Types: Issue Tracking, Vendor Advisory Added Reference Type GitHub, Inc.: https://github.com/modelcontextprotocol/typescript-sdk/issues/243 Types: Issue Tracking, Vendor Advisory Added Reference Type GitHub, Inc.: https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-345p-7cg4-v4c7 Types: Mitigation, Vendor Advisory -
New CVE Received by [email protected]
Feb. 04, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N Added CWE CWE-362 Added Reference https://github.com/modelcontextprotocol/typescript-sdk/issues/204 Added Reference https://github.com/modelcontextprotocol/typescript-sdk/issues/243 Added Reference https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-345p-7cg4-v4c7