CVE-2026-81094 mcp-router CLI before 0.6.3 Binds the MCP Aggregator to All Interfaces Without Requiring Authentication
The mcp-router CLI defaults to binding on all interfaces without authentication, exposing the MCP aggregator and fronted servers to unauthorized network access.
- 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-2026-81094?
CVE-2026-81094 is a critical missing authorization vulnerability in mcp-router, 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 mcp-router CLI served its MCP aggregator on every interface and enforced authentication only when the operator asked for it. The serve command in apps/cli/src/commands/serve.ts defaulted its host to the all-interfaces address on a fixed port, and required a token only when the corresponding flag was supplied, so a default invocation exposed the aggregator, and every MCP server it fronted, to anyone able to reach the port. Release 0.6.3 defaults the host to the loopback address and refuses to start without a token whenever the host it is given is not a loopback address; no earlier release carries either check.
Weakness: CWE-306
Which versions are affected by CVE-2026-81094?
How do I fix CVE-2026-81094?
No fix has been published for CVE-2026-81094 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-2026-81094 being exploited?
There is no known exploitation of CVE-2026-81094 in the wild and no public exploit code.
Sources
Also known as GHSA-g448-x63h-m2m3, GHSA-rx55-5c7h-r56r.