CVE-2026-81098
Telnyx MCP Server through 6.83.0 Missing Authentication on Streamable HTTP Transport
- State
- Published
- Severity
- 9.3 Critical
- Published
- Aug 27, 2026
- Updated
- Aug 29, 2026
- Reserved
- Aug 26, 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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 9.3 Critical | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N | VulnCheck |
| 3.1 | 9.1 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N | VulnCheck |
Weaknesses
- CWE-306 Missing Authentication for Critical Function
Affected Products
| Product | Versions |
|---|---|
telnyx-mcpteam-telnyx |
|
References
- https://github.com/team-telnyx/telnyx-nodeproduct
- https://github.com/team-telnyx/telnyx-node/pull/450issue-trackingpatch
- GitHub Security Advisory (GHSA-46jp-xr2h-fw7h)vendor-advisory
- VulnCheck Advisory: Telnyx MCP Server through 6.83.0 Missing Authentication on Streamable HTTP Transportthird-party-advisory
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