What’s Vulnerable › Vulnerabilities

CVE-2026-25536: @modelcontextprotocol/sdk has cross-client data leak via shared server/transport instance reuse

• Severity: high (CVSS 7.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-02-04 · updated 2026-07-15
• Weakness: CWE-362

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.

Affected products

• modelcontextprotocol typescript-sdk: from 1.10.0 before 1.26.0 — fixed in 1.26.0

How to fix

Upgrade to a fixed version: modelcontextprotocol typescript-sdk 1.26.0. Check the vendor advisory for mitigations.

References

• https://github.com/modelcontextprotocol/typescript-sdk/issues/204
• https://github.com/modelcontextprotocol/typescript-sdk/issues/243
• https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-345p-7cg4-v4c7
• https://access.redhat.com/errata/RHSA-2026:3960
• https://access.redhat.com/security/cve/CVE-2026-25536
• https://bugzilla.redhat.com/show_bug.cgi?id=2436937
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-25536.json

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