CVE-2026-81098: Team-Telnyx Telnyx-Mcp

Critical severity, CVSS 9.1. EPSS: 0.7% chance of exploitation in the next 30 days.

The Telnyx MCP server exposed its HTTP transport on every interface and did not require a caller credential. packages/mcp-server/src/http.ts served MCP on the root path with a listener bound to all interfaces and parsed the caller's authentication headers in a mode that did not fail when they were absent, so a request without any credential completed initialisation and dispatched tools. Dispatch forwarded the server's own stored credentials, the Telnyx API key and client secret together with the code-execution key, to the upstream endpoint, so an unauthenticated caller able to reach the port acted with them. The current code defaults the host to loopback, requires a server API key, and enforces it in middleware.

Affected products

Published 2026-08-27. Last modified 2026-09-24.