CVE-2026-81098 Telnyx MCP Server through 6.83.0 Missing Authentication on Streamable HTTP Transport
Unauthenticated attackers can access the Telnyx MCP server and execute tools using the server's stored API credentials due to missing authentication checks.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-81098?
CVE-2026-81098 is a critical missing authorization vulnerability in team-telnyx telnyx-mcp, published on 27 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-306
Which versions are affected by CVE-2026-81098?
How do I fix CVE-2026-81098?
No fix has been published for CVE-2026-81098 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-81098 being exploited?
There is no known exploitation of CVE-2026-81098 in the wild and no public exploit code.
Sources
Also known as GHSA-46jp-xr2h-fw7h, GHSA-j929-p4w2-gfw7.