Auth bypass in Team-Telnyx Telnyx-Mcp
CVE-2026-81098
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.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.007 (52.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 52.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.007 · change: +0.002
Affected products
Weakness classification (CWE)
References
- github.com/team-telnyx/telnyx-node (product)
- github.com/team-telnyx/telnyx-node/pull/450 (issue-tracking, patch)
- github.com/team-telnyx/telnyx-node/security/advisories/GHSA-46jp-xr2h-fw7h (vendor-advisory)
- www.vulncheck.com/advisories/telnyx-mcp-server-through-6.83.0-missing-authentic… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-81098?
- CVE-2026-81098 is a critical-severity vulnerability in Team-Telnyx Telnyx-Mcp, classified under Missing Authentication for Critical Function. CVSS score: 9.1/10. Published 2026-08-27.
- How severe is CVE-2026-81098?
- Critical severity. CVSS v3 base score is 9.1 out of 10.