CVE-2026-111770: MCP TypeScript server SDK: Shared transport or server instances delivered one HTTP client's messages to another
In affected versions, an MCP server reached over HTTP could deliver one client’s responses and notifications to another client. This happened when clients shared one stateless transport, or one McpServer or Server instance.
Messages were matched to a connection by JSON-RPC id alone. SDK clients number requests from 0, so ids collide in normal use.
References
- github.com/advisories/GHSA-jm63-cq47-j5jp
- github.com/modelcontextprotocol/typescript-sdk/commit/84804c22e45a662675a198f853b7f00063838a8d
- github.com/modelcontextprotocol/typescript-sdk/pull/2918
- github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-jm63-cq47-j5jp
- nvd.nist.gov/vuln/detail/CVE-2026-111770
Code Behaviors & Features
Detect and mitigate CVE-2026-111770 with GitLab Dependency Scanning
Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Dependency Scanning using SBOM also detects vulnerabilities from proprietary advisories that this site does not include. Learn more about Dependency Scanning using SBOM →