CVE-2026-81098
Severity CVSS v4.0:
CRITICAL
Type:
CWE-306
Missing Authentication for Critical Function
Publication date:
27/08/2026
Last modified:
27/08/2026
Description
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.
Impact
Base Score 4.0
9.30
Severity 4.0
CRITICAL
Base Score 3.x
9.10
Severity 3.x
CRITICAL