modelcontextprotocol typescript-sdk up to 1.25.x race condition

Summaryinfo

A vulnerability has been found in modelcontextprotocol typescript-sdk up to 1.25.x and classified as critical. This affects an unknown part. Performing a manipulation results in race condition. This vulnerability is known as CVE-2026-25536. Remote exploitation of the attack is possible. No exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in modelcontextprotocol typescript-sdk up to 1.25.x. It has been classified as critical. This affects an unknown part. The manipulation with an unknown input leads to a race condition vulnerability. CWE is classifying the issue as CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-25536 since 02/02/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Neither technical details nor an exploit are publicly available.

Upgrading to version 1.26.0 eliminates this vulnerability.

The vulnerability is also documented in the databases at EUVD (EUVD-2026-5335) and CERT Bund (WID-SEC-2026-0574). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

• IBM App Connect Enterprise

Productinfo

Vendor

• modelcontextprotocol

Name

• typescript-sdk

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15
• 1.16
• 1.17
• 1.18
• 1.19
• 1.20
• 1.21
• 1.22
• 1.23
• 1.24
• 1.25

Website

• Product: https://github.com/modelcontextprotocol/typescript-sdk/

CPE 2.3info

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CPE 2.2info

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Entryinfo

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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